ALBERT

Notes: Summary The ultrastructure of the adult digestive gland of Lymnaea stagnalis is described with references to light-microscopic observations. In the epithelium of the gland there are 6 different kinds of cells termed A, B, C, D, E, and F cells; mucous cells have rarely been observed. A cells: They are undifferentiated and represent precursors of other cells in the digestive gland. B cells: The numerous B cells contain vacuoles of different size and structure, in which the food is digested. C cells: These cells have been called lime cells by earlier authors. However, it is not possible to detect calcium in them with alizarin red S or nuclear fast red, though some cells in the connective tissue which surrounds the gland contain calcium. The C cells contain vacuoles with a fine osmiophilic inclusion and a strongly marked endoplasmic reticulum. They are presumably secretory cells. D cells: Different stages of D cells can be observed. They contain all characteristical inclusions, called excretory granules. These are extruded to the lumen of the gland as soon as the cell has reached a certain size. E cells: The cytoplasm of the cylindrical E cells is restricted to the marginal region of the cell and the area of the nucleus. The cell contains much glycogen and osmiophilic droplets which presumably consist of lipid. The E cells seem to store these substances. F cells: These cells possess large apical cytosomes and a reduced cytoplasm. Two distinct functional possibilities have to be considered with regard to the ultrastructure of the cells. The F cells could be resorbing cells or they may represent an intermediate stage of other cell types. In the discussion, it is provisionally concluded, that the B, C, and D cells are distinct cell types.

Notes: Summary 1. The diameter of the eyes of Nannacara anomala increases faster than the length of the body until the 5th–10th day after hatching; after this time the growth of the eyes is negatively allometric. 2. The overall thickness of the retina is greatest in the temporal region of the eye for the complete period of development; it decreases toward the dorsal, central, and nasal parts and is least thick in the ventral sector. The same is true for the regional differences in the quantitative distribution of the various retinal cell classes. This means that a so-called “area” exists in the mediotemporal part of the eye of Nannacara anomala. 3. During development the number of receptor cells per unit area increases to twice its original value, whereas the number of ganglion cells decreases by a half. 4. The average ratio of the different cell classes of the adult retina is: 2 (receptor cells): 0.5 (horizontal cells): 2 (bipolar cells): 2 (amacrine cells): 1 (ganglion cell). 5. In the “area” the density of the population of visual cells is 30% higher than in the periphery of the retina. 6. When the larvae start to swim freely (5th day) there are two completely differenciated cone types (single and identical double cones) in the “area” which are arranged in a square pattern. Functioning rods are not found until the 16th day after hatching. 7. The retinomotor response of single cones and rods can be observed after the 16th day. 8. A temporal sequence of 6 different stages in the development of the visual cells is distinguished in the fundus of the eye. At a certain age the same stages are found as a spatial sequence in the peripheral zones of additional growth. 9. The extent of the growth zones corresponding to the different stages of differenciation of the receptor cells during the course of the development of the eye is studied in reconstructions of serial sections. The growth of the visual cells is most advanced in the mediotemporal “area” and most delayed in the ventral part of the retina. 10. The regional differences in the development of the retina are discussed with respect to ethological and sensory-physiological findings in young Nannacara.

Notes: Summary The fine structure of the visual clubs was studied in two species of the family Otoplanidae, Otoplana truncaspina and Notocaryoturbella bigermaria. These clubs, which are found inside the cerebral capsule, are characterized by the presence of a disk-shaped photoreceptor process containing membranous laminar or tubular whorls. These cover both faces of the disk. A thin cytoplasmic layer is found between the two faces. This continues with projections which surround the disk border. The major projection, containing the nucleus, shows Golgi apparatuses, numerous vesicles of smooth endoplasmic reticulum, multi-laminar bodies, and mitochondria localized in the region bordering the disk cytoplasm. There are no pigmented cells. The affinities with other cerebral photoreceptors are discussed.

Notes: Summary 1. The diverting system in the salivary glands of diplopoda begins at the intercellulary spaces between the secretory cells. Here extrusion of the secretory vacuoles takes place. Sometimes microvilli of secretory cells protrude into the intercellulary spaces. 2. Lateral ducts unite and open into the intercellulary spaces. They are formed occasionally by a single wall-cell and represent intercellulary tubes lined with a cuticle. They run throughout the cell into a wide, common main efferent channel. 3. The main efferent channel is composed of many wall-cells lined with a cuticle, and usually opens into the preoral cavity. 4. The ultrastructure of the wall-cells is described. They give the impression of inactive cells, however discernible free ribosomes are numerous. Some glands possess characteristic myeline-like bodies. 5. As a rule, wall-cells represent a single-layered epithelium resting on the secretory cells of the salivary gland. At the efferent duct between wall-cell and a secretory cell a zonula adhaerens is always developed, subsequently to it septate desmosomes. Neighbouring wall-cells are linked together by septate desmosomes.

Notes: Summary The patterns of arrangement of connective tissue fibres and muscle fibres were recorded in the anterior tail region of three newt species, Triturus cristatus, T. alpestris and T. vulgaris. In the axial connective tissue, arrangements are found well adapted to impede other movements than lateral flexion and thus in agreement with similar systems present in fishes and lower chordates. The arrangement as well as the total amount of perimysial fibres in the newt's tail show a close agreement with the same characteristics of perimysial connective tissue in the m. lateralis of fishes. As in fishes we may expect these fibres to play a distinct part in the establishment of a firm contact between axial skeleton and lateral muscle mass. In the lateral musculature of the newts studied, the helical patterns of arrangement of the muscle fibres, seen in fishes, were absent. The patterns present are not in accordance with a uniform degree of contraction of the muscle fibres throughout the lateral musculature but they do show a tendency in that direction. It is suggested that in adult newts the muscle fibres show more diversity in their physiological characteristics than in fishes and amphibian larvae.

Notes: Summary Internal fertilization (in metaccelom) generally occurs in Phoronida. The eggs are extruded to the exterior through the nephridia, shed freely into the sea-water or retained in the lophophoral concavity. The cleavage of phoronid eggs is total, equal (or subequal) and radial (with sometimes fortuitous appearance of spiral cleavage patterns). The gastrula is formed by emboly. The mouth is derived from the anterior remnant of the blastopore without a true stomodeum. The anus arises by perforation, as an independent structure of the blastopore. The mesoderm formed by budding originates as isolated cells proliferated from the anterior and lateral surfaces of the archenteron. In the preoral hood appears a protoccel by mesodermal cells lining the walls of the blastoccel. The trunk cœlom (or metaccel) of Actinotrocha originates from one or two posterior masses of mesodermal cells. It is possible that the mode of formation of this coelom varies in respect to the different species. The mesoderm elaboration is considered as a modified enteroccelous method. The acceptance of Phoronida as deuterostomes is regarded as the logical consequence of the present considerations (see also Emig, 1973): radial cleavage, origin of mesoderm by a derived enteroccelous method, trimetamerous actinotrocha.

Notes: Summary In the early pupal stage (48–60 h after moulting) of the leaf-cutter bee Megachile rotundata, the pairs of centrioles in the retinula cells are proximal to the nucleus, far away from the rhabdom which is developed only in distal areas at this stage. The centrioles are aligned perpendicular to another with the distal centriole parallel to the longitudinal axis of the ommatidium, or are in transitional positions tending to a tandem. According to earlier investigations (Wachmann et al., 1973) this is the final stage. Once this position is obtained the first root fibrils appear and unite in a root fibre as progress towards the imaginal cell stage continues. It is still not known at what stage Tubuli or fibrils extending in a distal direction first appear. The results indicate a high probability that the centrioles involved in mitotic cell divisions are identical with those transformed to ciliary structures in the imaginal cell stage. It was not possible to demonstrate any connexion between the centrioles and the developing microvilli of the rhabdomeres.

Notes: Summary An investigation of the biology and anatomy of the mite family Bdellidae (Trombidiformes) included a study of the mating behaviour and the genital system of ten species. 1. In the Bdellids insemination takes place with the aid of spermatophores. Spermatophores of species of all four subfamilies were observed. Cyla latirostris (Cytinae) forms simple spermatophores, each with a non-covered sperm drop on its top. Two other types of spermatophores are described, i.e. those of a) Spinibdellinae, and b) Bdellinae and Odontoscirinae. In both types the sperm liquid is covered by a secretion similar to the material forming the stalk of the spermatophore. In Bdellinae and Odontoscirinae a “penis” is extruded during deposition of the spermatophores. 2. The eggs of Bdellids are deposited at sheltered places by means of an ovipositor. Spiny globular and reddish eggs have been observed in all subfamilies. The eggs of Biscirus (flat, lenticular), Spinibdella cronini (thin-shelled, globular, with a spun protective covering) and Bdellodes longirostris (globular, tuberculated, whitish) are different. The eggs of these species have no spines. 3. A comparative study of the complicated male genital system is given. Striking anatomical differences distinguish the group of Bdellinae and Odontoscirinae from the group of Cytinae and Spinibdellinae. The shape of the sperm cells is also different in the two groups. The secretion produced in the genital tract or accessory glands is formed to a specific spermatophore by means of the so-called penis, which in Biscirus, Bdellinae and Odontoscirinae acts as a matrix to build up the head of the spermatophores. 4. The genital system of the female is described. After entering pouches (“follicles”) which are built up by the ovarian epithelium, yolk and yolk-shell can be observed in the oocytes. The secreta of the external eggshell are produced in the unpaired oviduct, which is divided into two parts (oviduct I and II). The mature eggs are stored in the oviduct I until deposition. The development of the eggs reaches this state even without previous insemination. The sperm is taken up by the female by means of the ovipositor, which has a specific receptaculum seminis (Cyla latirostris excl.) at the distal end. There is no communication between receptacle and oviduct. In the opisthosoma of the adult Bdellid female lateral groups of basophil staining cells similar to those described in several trombiforme mites were observed. The function of these cells is still unknown.

Notes: Summary The irregular Clypeastroida include both species with highly ovate tests, high lanterns and arched, nearly vertical located teeth, and species with flattened tests and straightened, slender and horizontal orientated teeth. Irrespective of form and orientation of the teeth the tooth-elements of Clypeastroida, are built up following the same construction (Fig. 1). The tooth is devided by the small abaxial (ab) and the large adaxial (ad) tooth part. The adaxial part consists of prisms (P) and of lateral plates (LP). In Clypeastroids the teeth do not protruded out of the mouth. They are used for chewing but not for feeding. Echinoid teeth are built of calcite, but they are considerable stronger than compact calcite. The tooth of Fellaster zelandiae demonstrates that it is the true tooth, built up as composite material, which is extreme hard. The calcareous appendage of polycristalline calcite is only as hard as compact calcite. In chewing the clypeastroid teeth are exposed to compressive stress only, which acts in the axis of the teeth. The chewing area in most species is built up both by prisms and by lateral plates. But in some species it is built up by prisms only (Dendraster, Mellita) and in other species by lateral plates only (Fellaster, Echinodiwus). The Vickers-hardness (HV) of the teeth is not influenced by these differences. The suborders given by Durham (1955) are discussed and accepted. But the Rotulidae-despite some aberrant properties-are proposed to be classified into the suborder Laganina by means of the structure of their teeth and other characters. The present work verifies the formerly expressed opinion that Clypeastroida are belonging to a monophyletic group of their own, which is considered to be a sister group of the recent regular echinoids. On the basis of morphological studies the Clypeastroida-contrary to the hypothesis of Durham and Melville (1957)-are said to be not derivable from cidaroid ancestors or descendants of cidaroid ancestors.

Notes: Summary Autoradiographs show that there is an essential difference in the capacity of the endo- and ectoderm of A. sulcata to absorb dissolved amino acids. Most of the dissolved organic substances absorbed by the ectoderm remain there, while a smaller part is immediately translocated to the endoderm. The shift of particulate food, resorbed by the endoderm, occurs slowly. In discussing the ability to absorb dissolved organic combinations from seawater, we can say that the actinians are very well adapted to their habitat, in relation to the varied ability of their endo- and ectoderm to differentiate cytologically; the ectoderm, whose surface is extremely enlarged by microvillies, is continuously in contact with dissolved organic compounds.

Notes: Summary Diagnosis of Apatronemertes nov. gen. Hermaphroditic freshwater lineid heteronemerteans with no eyes, frontal organ or caudal cirrus; outer longitudinal muscle layer mingled with dermal zone, but loosely developed into outer and inner layers separated by dermis; body-wall with outer longitudinal muscle layer externally bounded by thin outer circular muscle zone which extends precerebrally; cephalic glands well developed, ventrally extending beneath the brain; proboscis with outer circular and inner longitudinal muscle layers and two fibre crosses, one more obvious than the other; rhynchocoel three-quarters of body length and rhynchocoel musculature not interwoven with body wall muscles; dorsal cerebral ganglia with posterior fibrous bifurcation, the cerebral organs being attached to the more ventral branch; nervous system without neurochords; excretory system a complex arrangement of ducts and cells, discharching into the gut via specialised cells; blood system extensive, with a postcerebral vascular plexus intimately associated with the excretory system.

Notes: Summary 1. In the lateral pterothoracic region of the Hydrocorisae, the features which vary most are the position of the metathoracic spiracle, the structure and position of the intersegmental boundary, and the size and distribution of 1. the concealed subalar and intersegmental air spaces and 2. the exposed ventral thoracic air layer. Since not all of the observed variations appear to reflect phylogenetic relationships they must be at least partly due to functional differences. 2. The metathoracic spiracle lies in the posterior part of the mesothoracic epimeron and may occupy any one of three positions. In representatives of the Belostomatidae, Nepidae, and Gelastocoridae, and in some Naucoridae, it faces the lateral intersegmental air space (Position 1). In Cryphocricos and Limnocoris (Naucoridae) it faces the small ventral intersegmental air space (Position 2), while in representatives of the Notonectidae and Corixidae it faces the subalar air space (Position 3). The subalar or lateral intersegmental space onto which the spiracle faces is often enlarged by the invagination of the circumspiracular part of the epimeron into the body. 3. The lateral intersegmental boundary projects sharply anteriorly, into the mesothoracie cavity, in most of the Hydrocorisae examined. Among the Naucoridae this characteristic varies both intergenerically and intragenerically. In Gelastocoris (Gelastocoridae) and in at least some species of Cryphocricos and Limnocoris the boundary appears to shift anteriorly during postecdysial development. A possible reason for the anterior displacement of the boundary is that it provides a greater surface of origin for one of the large extrinsic muscles of the hindleg. This may also explain the unusually ventromedial position of the metathoracic spiracle in Cryphocricos and Limnocoris. 4. In Belostoma (Belostomatidae) and Ranatra (Nepidae) the metathoracic spiracle is not highly porous and the concealed thoracic air spaces do not appear to serve as oxygen sources for underwater respiration. They probably protect the spiracle against entry of water, however, and play a role in hydrostatic balance and pressure reception. 5. The respiratory significance of the pterothoracic variations in other Hydrocorisae is more difficult to assess without more information on such subjects as spiracular fine structure and function. It is here suggested, however, that the size of the concealed air space onto which the metathoracic spiracle faces may be related to the extent to which an aquatic bug is dependent upon atmospheric oxygen. Most Hydrocorisae are buoyant and their concealed air spaces are large. “Slow-water” Naucoridae appear to be of this type. In Aphelocheirus (Naucoridae), however, the concealed air spaces are small and the insect is heavier than water. A thin, exposed air layer, covering much of the body, obtains enough dissolved oxygen to make Aphelocheirus independent of atmospheric oxygen. Some other “fast-water” Naucoridae, such as Cryphocricos, which cannot easily reach the surface of the water, show a similar reduction of the concealed air spaces and a consequent decrease in buoyancy. This suggests that they, like Aphelocheirus, rely less upon atmospheric oxygen than upon dissolved oxygen obtained by their exposed air layers.

Notes: Summary Each body pore in Chromadorina germanica females was found to lead through a canal to an epidermal gland and an associated bipolar neurocyte. The epidermal gland is a unicellular merocrine organ. Typical Golgi bodies were not found in this cell type, but multivesicular complexes may represent their functional equivalent. Several types of secretory vacuoles were observed. The contents of immature vacuoles consist of very fine granular material which is transformed in tubular elements. During this process the membranes of the vacuoles are coated by globular vesicles. Electron-dense material is deposited on the inner surface of mature vacuoles. The tubular secretion is released in the common duct of gland and neurone. 2 ciliary processes are located in this duct. They are implanted upon the dendrite of the neurocyte. The orientation of the secreted tubules is preferentially parallel to the long axis of the cilia. The axon of the neurocyte is accompanied by a slender, elongated glia cell. The significance of the extracellular tubules is discussed by comparison to similar phenomena in a variety of other organisms. It is concluded that the system of gland and neurone constitutes a functional unit.

Notes: Summary The morphology and histology of the tarsi of Tettigonia viridissima L. was examined and the mechanical function of the tarsus as a clinging, snatching and adhesive organ as well as its sensory function is explained and discussed. The tarsus consists of a pretarsus with a pair of claws and an adhesive claw-plate and four tarsal segments known as tarsalia, which are fed by a common haemocoelic space and a branched tracheal system. With the exception of the distal tarsalium, all tarsal segments have paired adhesive pads called euplantulae on the ventral side. These reveal layers that differ histologically because of their adhesiveness: an exocuticle made up of little plates, a tubular endocuticle, a structureless X-layer, and epithelial Y-layer, and a strongly folded epidermis. The tracheal trunk expands into air sacks in the euplantulae. The movement of the tarsus occurs via two short muscles in the distal tibia region and via a long sinew which is attached to the adhesive claw-plate and made taut by muscles in the tibia and femur. Adhesiveness is produced by the adhesive properties of the saliva which is regularly used to moisten the tarsi of these insects. There are numerous sense organs localized on the tarsi. Numerous sensilla trichodea and sensilla campaniformia are situated on the dorsal side, acting as mechanoreceptors. On the joints both types of sensilla are found close together fulfilling a special function as joint-receptors. On the euplantulae there are sensilla complexes composed of 2–4 sensilla basiconica arranged in rows. These probably act as contact chemoreceptors.

Notes: Summary The heart and peripheral vessels (branchial circulatory system) of living parabiotic newt larvae (produced by the fusion of neurulae), were observed under the microscope. The heart rate was determined and a special analysis of the functions of the circulatory organs (i.e. heart contractions with a microkymograph velocity of blood flow, etc.) was carried out. Some of the hearts taken from parabionts were similar to those of the normal control animals in stage of development, position and function, while others deviated sharply from the controls. The hearts were classified into the following eight categories: Type I: separated hearts for each partner; Types II–IV: partial duplication of the organs; Type V: one common heart for both partners; Type VI: two variously differentiated organs; Types VII–VIII: underdeveloped or rudimentary hearts or none. A rhythmically accented form of contraction is present in a normally developed parabiotic heart, whereas in undifferentiated organs there is still a peristaltoid action. According to heart type, the circulation in the branchial system is normal, or slower or even stagnant, in comparison to the control animals. Disturbances in circulation can affect either one or both partners. Partial duplication of the organ with a strictly synchronous rhythm (Types II–IV) offers the most favorable hemodynamic conditions. Hemodynamical conditions are less favorable in separate hearts that have a predominantly asynchronous rhythm (Type I) and in common hearts and variously differentiated hearts; hearts in categories VII and VIII are completely inadequate. The decisive morphological and functional factors in the varied hemodynamic conditions in the parabionts are discussed and general questions concerning the development of the heart in parabiosis are also mentioned.

Notes: Summary 1. Examination of the marginal region of the compound eyes of orthorrhaphan Brachycera and Cyclorrhapha (Diptera) revealed special ommatidia with unusually thick central columns from rhabdomeres. (The cross-sectional area of the column is 1.3-17 times the normal size according to species; morphometric data on this and points 4–7 are given in Table 1.) These special ommatidia existed in all our 29 species from 13 families (4 from orthorrhaphan Brachycera, 9 from Cyclorrhapha). 2. The thickened form of the column is not the result of light adaptation. 3. Both a ♂♂ and ♀♀ of 13 species were examined, and the special ommatidia were confirmed in both sexes. 4. The special ommatidia were found in the compound eyes of Haematopota italica and Haematopota pluvialis (both 4 4, Tabanidae), Rhagio scolopacea Rhagionidae), Eristalis tenax (♂♂ and ♀♀ , Syrphidae), and Calliphora erythrocephala (♂♂ , Calliphoridae) almost exclusively in the marginal region near the dorso-lateral parietal area, the vertex, and the frons. The density of population of the special ommatidia is greatest near the vertex and the upper frons. In the other species of flies the special ommatidia were always observed at least in these marginal areas of the compound eyes. 5. Three-dimensional reconstruction of the central column from rhabdomeres in the special ommatidia shows that each column consists exclusively of no. 7 and no. 8 rhabdomeres (after the numbering of Dietrich, 1909). The two rhabdomeres are arranged either in “tandem” form (as normal) or they are interdigitated, thus forming the column of multiple segmentation in a longitudinal direction. 6. In this tandem column the transit position from the distal to the proximal rhabdomere, and also the proximal end of the whole column is often more distal than normal. 7. The segments of the interdigitated column get shorter and more numerous the nearer the column is located to the margin of the compound eye. 8. In view of its position usually nearer than normal to the dioptric apparatus in both architectonic forms it is possible that the no. 8 rhabdomere of the special ommatidia absorbs more light than the no. 8 rhabdomere of the normal ommatidia. 9. Peripheral rhabdomeres no. 1-no. 6 in the marginal area of the compound eyes are often reduced in size in both the special and the normal ommatidia and some of them are absent in the special ommatidia. 10. The structure of the dioptric apparatus in the special ommatidia seems to be the same as in the normal ommatidia. 11. Morphologically intermediate forms of the central column were found in the ommatidia of the transitional zone between the special marginal ommatidia and the nearest normal ommatidia. 12. The interdigitated form was observed mainly in the phylogenetically “older” families of flies examined, while the tandem form was found predominantly in the “younger” families (Fig. 22).

Notes: Summary The integumentary glandular system of Claviger testaceus is made up of glandular units which are isolated from each other, are grouped in glandular patches or are joined together as multiple glands. These glandular units belong to two basic morphological types: A and B. Type A glandular units are made up of 3 cells in a row. Their structure resembles that of glandular units of many other insects. Isolated units of type A are found scattered under practically the whole surface of the cuticle. Their density varies from 10 to 15 units/10−2 mm2 in most parts of the insect's surface. However, this density may reach 24 units underneath the antennal disc, and 27 to 66 units/10−2 mm2 underneath the trichomes. Certain units of the antennal disc possess a chimney-shaped pore. Multiple glands made up of type A units exist in the head and in the abdomen. They are always associated with noticeable external cuticular structures. In the head, two paired groups of labral glands open at the reticulated surface of the labrum; some units of these glands open also in a groove on the outer edge of the mandibles. Mandibular glands end at the same locations, but most of their units reach the outer edge of the mandibles. It is suggested that these cephalic glands could play a role during trophallactic exchanges between ants and the beetle. The hypopharyngeal gland may have a salivary function. Among the abdominal glands, the paired mediotergal glands open into a large median tergal depression located at the anterior half of the abdomen. The three lateral paired glands (or Wasmann's glands) end near the trichomes, one of them in a sizeable external reservoir, surrounded by the abdominal trichomes. Previous observations of the behavior of ants towards Claviger could be interpreted by suggesting an appeasement function for Wasmann's glands. The mediotergal glands most probably also play a function in host-guest relations. The glandular units of the mandibular and hypopharyngeal glands look very similar to the isolated type A units. The units of the other glands differ in precise structure and proportions. Type B glandular units are one-celled and gland cells similar to them have only rarely been described in the literature. Some isolated type B units are found at the joints. At the most important joints, they are joined together as multiple glands. Their function is most likely to secrete a lubricant. Under the sides of the tergite VIII of the female, which, when stationary, are covered by the sides of sternite VIII, there exists a pygidial glandular patch of type B units of the same structure as those of the joints. These units may also have a lubricant function or play a role in the reproductive behavior of the species. Elsewhere the precise structure of the type B cells vary with their location. They are most numerous underneath the trichomes (57 to 114 units/10−2 mm2) and the antennal disc (57 units/10−2 mm2). Underneath the rest of the insect surface their density varies from 7 to 42 units/10−2 mm2. The highest densities are observed not far from the openings of multiple glands, which appear to secrete allomones acting during host-guest relations, e.g. the labral glands, the mediotergal glands and Wasmann's glands. In most parts of the insect's surface the type B cells outnumber the type A cells.

Notes: Summary The caudal gland apparatus in Chromadorina germanica females usually consists of three unicellular units surrounded by a basal lamina; sometimes a fourth cell of unknown nature, lacking a duct, is present in the gland region. The following observations were made in these studies: In the specimens examined the nuclei of the anterior, cells are large with prominent nucleolus. The nucleus of the posterior cell is smaller and contains condensed chromatin. When a fourth nucleus is present., its morphology resembles that of the posterior gland cell. The cytoplasm is rich in rER and mitochondria; typical Golgi bodies were not observed. Filamentous microvilli containing dense particles project in the ramifications of the gland lumen; secretory granules are formed by condensation of these particles. In the posterior part of the tail the duct of the anterior cell is located ventrally and those of the posterior cells dorso-sublaterally, with a longitudinal muscle in between. This muscle is thought to be the spinneret retractor. The tail extremity consists of a terminal tube, separated from the gland ducts by the spinneret plug. Two very short subterminal setae are implanted on the tube. A possible secretory cycle is deduced from light microscopic observations and from the differences in ultrastructure in the 3 gland cells.

Notes: Summary Osteoglossum ferreirai is a mouth breeding species. In the first stage of development the young is a tiny fish, at first colourless, nourished by an enormeous yolk sac. The main period of growth is marked by characteristic black and white streaks along the body of the fish. The stripes disappear when the fish becomes adult. A series of photos shows these colour changes and the resorption of the yolk sac. The biological significance of the juvenile colour of Osteoglossum ferreirai is discussed with reference to mouthbreeding and to the shoaling of the young fishes of Osteoglossum ferreirai.

Notes: Summary The different cell types of the young postgastrulate embryo ofLymnaea stagnalis L. were studied by light- and electron-microscopy. Vacuoles containing perivitelline fluid were observed in all cell types of the ecto- and entoderm, but not in mesodermal cells. In the region of the midgut, cells with large vacuoles store the extraembryonic nutriment. They take up the perivitelline fluid from the gastric lumen by means of macropinocytosis. Micropinocytosis also occurs, just as in the other entodermal and most of the ectodermal cells. With the PJS-reaction and the treatment with ferritin we can demonstrat that various cells of the embryo contain galactogen—a constituent of the perivitelline fluid-in the cytoplasm apart from the vacuoles. The differing content of extraembryonic nutriment in the various kinds of cells is thought to be connected with their different performances. The electron-microscopic demonstration of acid phosphatase activity indicated digestive processes in the embryo. In all cells many yolk granules were observed. Most of them seemed to be involved in the cell metabolism. In part of the granules phosphatase activity occurred. The perivitelline fluid is the main nutrient reserve for the embryo. The yolk granules are subordinated with regard to the quantitative aspect of embryonic nutrition.

Notes: Summary 1. The main purpose of the present investigation was, through a study of the anatomy and the histology of the Apistobranchidae, to shed some light upon the systematic position of this polychaete family. 2. The results of the anatomical investigation of the apistobranchids were compared with corresponding observations on other sedentary polychaetes and some archiannelids; the significance of these results as phylogenetic-systematic characteristics was evaluated. The form and the position of the body cavities and the topography of the nervous system seem to be the only features to which we can attach any importance, at least for the present. 3. The interpretations of the systematic position of the apistobranchids given by earlier authors and based on the outer morphology were evaluated. This showed that many of the arguments for a closer relationship between the apistobranchids and the chaetopterids, the paraonids and, above all, the orbiniids were rather unconvincing. 4. Nor could the results of the present studies of the anatomy be interpreted as indicating that the nearest relations of the apistobranchids should be sought among the three families mentioned above. On the other hand, striking anatomical resemblances were found to exist between the apistobranchids and the spionids and, above all, between the apistobranchids and the trochochaetids. 5. We point out that the above results of the anatomical investigation of the apistobranchids agree completely with Friedrich's (1940) view (based on data in the outer morphology) that there is a close relationship between the apistobranchids and the trochochaetids. 6. As certain features in the morphology and the anatomy of the apistobranchids seemed to shed some light upon the systematic position of the Archiannelida, this much-debated problem was more closely discussed. Here it was emphasized that the morphological and anatomical characteristics that earlier authors most frequently put forward as evidence for retaining the Archiannelida as a systematic category were not valid. Furthermore, it is shown that this also applies to the arguments advanced by Heider (1922) and Hermans (1969). Finally, we point out that Hatschek's (1893) idea of a closer relationship between Protodrilus and the spionids finds definite support in some facts given in the present paper.

Notes: Summary The fine structure of the pair of large and complex cerebral ocelli of Vanadis tagensis is described. The primary retina with its component photoreceptoral and supportive cells can be divided into four principal layers. Beginning from the basal lamina encapsulating the eye, these are the plexiform, nuclear, pigmented, and receptoral layers. Each photoreceptor consists of an array of densely packed microvilli 6 μm in diameter projecting radially from a cylindrical photoreceptoral process extending about 80 μm into the optic cavity in. the center of the ocellus. A large striated rootlet, 0.5 μm in diameter, and numerous microtubules extend the length of the process. A basal body, without a cilium, has been observed at the tip of the striated rootlet. Long straight microvilli from the supportive cells extend the length of the photoreceptoral processes between the microvilli of adjacent photoreceptors. The shading pigment of the pigmented layer is located in both types of cells. Nuclei of the supportive cells are closer to the pigmented layer and one seventh as numerous as those of the photoreceptoral cells. The supportive cells are irregular in shape and packed with filaments ending in large desmosomes along the proximal border of the pigmented layer. Opposite the primary retina a pigmented iris surrounds the pupil, except on one side where a small group of cells, the secondary retina, is situated. Between the primary and secondary retinas is the apex of a large secretory cell whose cell body lies between the plexiform layer of the primary retina and the basal lamina. The large, spherical, compact lens occupies but does not fill the optic cavity. The true structure of the material in the remainder of the optic cavity has not been determined. These eyes are compared to the descriptions of the cerebral ocelli of cephalopods, onychophorans, and phyllodocidan polychaetes.

Notes: Summary 1. The egg cells, or oocytes, of Trichoplax adhaerens probably derive from cells of the ventral epithelium. They leave the epithelial layer and go through their growth phase within the interspace between both epithelia. 2. During the growth phase the egg cells are surrounded by fiber cells, which evidently have a nutritive function. 3. Characteristic of vitellogenesis is the appearance of cortical granules which participate in the formation of the “fertilization membrane”. 4. A new cell type is described and the possibility that it is a sperm cell is discussed. 5. Trichoplax adhaerens has a very primitive mode of oogenesis, reminescent of that of the sponges (Parazoa).

Notes: Summary The antennae of the worker of Camponotus vagus bears sensory articulated setae on the last article of the funiculus; each of them is innervated by six neurons. The six dendrites are initially surrounded by a common cuticular sheath which divides into two by an invaginating process. One, with the largest dendrite inside, extends to the articulation, and shows an apical densification characteristic of mechanoreceptors. The second cuticular sheath surrounds the five other dendrites and reaches the apex of the seta, which is open by only one pore. The dendrites are not ramified. The double sensory function of the receptor is discussed.

Notes: Summary Sperm transfer in Boreus westwoodi Hagen is accomplished by means of a spermatophore. 2. The spermatophore of Boreus westwoodi has a spindle-like shape. It is divided by a median partition into two chambers situated side by side. Each chamber runs out into a separate sperm tube. 3. The sperm is probably expressed by the swelling of a granular substance which fills out the anterior three-quarters of the spermatophore. 4. The spermatophore is produced in the genital ducts of the male during copulation. 5. During sperm transfer the spermatophore remains in the interior of a membranous aedeagus with the exception of its tip, which is introduced into the orifice of the ductus receptaculi. Thus the spermatophore of Boreus westwoodi is functionally a component of the male copulatory organ. It is to be regarded as an elongation of the aedeagus and functions additionally as a device to force out the sperm. This guarantees safe sperm transfer without loss. 6. Since the sperm pump is obviously absent in all species of Boreus it can be assumed that the sperm transfer by means of spermatophore is a characteristic feature of the whole family, in contrast to the situation found in all other families of Mecoptera, all of which have sperm pump and thus transfer fluid sperm. 7. Since the author starts from the assumption that the last common ancestral species of the living Mecoptera had at least a primitive apparatus for expressing fluid sperm, the spermatophore of Boreus westwoodi is regarded as a convergent development in relation to the groundplan of Pterygota. The author does not exclude the possibility that the stem group of the Mecoptera had retained the ability to form a sperm packet surrounded by a secreted substance. There may have been sperm packets in which the surrounding secretion substance did not harden, and which were expressed by a primitive sperm pump. In this case the redevelopment of a solid spermatophore after the loss of the sperm pump could be explained as a continuous process. 8. The author presumes that the redevelopment of a spermatophore in Boreus westwoodi is connected with the formation of a secondary ovipositor and the correlated caudal shift of the opening of the genital chamber in the female.

Notes: Summary In the stick-insect Carausius morosus Br., a first atypical cuticle is secreted at an early stage by the epidermis of the germ-band. A second cuticle appears just as the dorsal closure of the embryo is being completed and there is no ecdysis of the first cuticle. A third cuticle is secreted about ten days before hatching: it is the first larval cuticle. The ecdysis of the second cuticle occurs at the time of hatching. We tend to think that hatching is triggered by the ecdysis behaviour. The concepts of “embryonic moulting” and of “embryonic moulting cycles” are questioned by our own observations and by discrepancies in some previous work.

Notes: Summary To settle the point at issue concerning the systematic position of the isopod family Tylidae one representative of each suborder in question (Valvifera: Mesidotea entomon, Oniscoidea: Ligia oceanica) and one member of the Tylidae (Tylos latreillei) were investigated concerning their skeleton and appendage-musculature of the cephalothorax. The results are compared with the findings up to now known from other malacostracans. The following items are considered as the more important results of this investigation: 1. The endoskeleton of all three isopods consists as in all isopods investigated by now of a maxillary apodeme and a maxillipedial apodeme. The former takes its origin ventrally between the insertions of the two maxillas, and consists of a basal plate that is dorsally divided into a frontal arm and a caudal plate. The frontal arm is fastened to the roof of the head by connective tissue, the caudal plate serves as bearing surface for the gut. The second apodeme is an irregularly fringed plate that takes its origin dorsolaterally between the caudal margin of the head and the tergit of the maxillipedial segment. In Mesidotea there exists a third, small apodeme, originating at the base of the cleft on the sides of the head. 2. In the labrum of each of the three investigated species a sclerotized clasp was found which has not yet been described in isopods. These sclerites are only laterally and medially connected with the epipharynx. At their lateral ends the transverse muscle inserts. 3. In Ligia oceanica the clypeolabral musculature is developed asymmetrically, which is seen in connection with the asymmetry of the mandibles. Moreover, the adductor of the labrum tip does not originate at the frontal plate as in all other isopods that have been investigated in this respect, but takes ist origin at the proximal fold of the clypeus. 4. The strongly reduced first antennae of Ligia and Tylos possess both still an antagonistic pair of muscles. The function of the first antennae in Tylos is completely obscure. 5. The pedunculus of the 2nd antennae consists of 6 articles in the three investigated forms as this is primarily the case in all isopods; in other malacostracans there are at most 5 articles which correspond to the five distal articles of isopods. The first (proximal) article consists of a dorsal and a ventral part; in Mesidotea the ventral part can be moved separately with regard to the head capsule, in Ligia and Tylos there is a rigid connection. In Ligia and Tylos the dorsal part has developed an apodeme which serves for the attachment of several muscles. 6. The asymmetrical mandibles are dicondyle, the head (condylus) of the joint being formed in both cases by the mandible, which is not the case in the Dikonophora (Tanaidacea), for example. A muscle which originates and inserts in the mandible is interpreted as belonging originally to the mandibular palp which is, however, reduced in all three investigated species. In Mesidotea there are still two abductor muscles (plesiomorph condition) whereas in the two other species one abductor is reduced. 7. The first maxilla has a basal sclerite which is let in deep into the interior of the head, just beside the maxillary apodeme. With regard to the musculature of the first maxilla the three forms agree largely, also from a functional point of view. 8. The 2nd maxilla in Mesidotea consists of 5 sclerites which have mobile articulations with each other, and of three mobile endites; the complicated musculature is made up by 9 muscles. The 2nd maxilla of Ligia and Tylos is, compared with the condition in Mesidotea, strongly modified, the sclerites and endites are fused together, there is only one free basal sclerite, the musculature is reduced to 4 (Ligia) resp. 2 (Tylos) muscles. 9. The maxillipes in Mesidotea possesses a complex basal muscle equipment which allows allround movements; in the endopodit there is an articulation between ischium and merus and between carpus and propus with the corresponding adductor- and abductor-muscles. On the other hand in Ligia and Tylos there is a reduced basal musculature and a frontally archlike extended insertion of the basis; this allows only slight dorsoventral movements of the extremity. Additionally, the articulation between carpus and propus is reduced in the endopodite of the latter forms. In Mesidotea the endite of the basis is equipped with a coupling-hook, which is missing in the other two species. 10. 33 synapomorph characters could be found for Ligia and Tylos compared with Mesidotea, whereas the similarities between Mesidotea and Ligia resp. Tylos could all be shown to be symplesiomorph. Thus it is made sure that the family Tylidae has its nearest relatives not in the suborder Valvifera but with all probability is in a consequently phylogenetic system to be counted to the Oniscoidea.

Notes: Summary 1. It is suggested that the eedysial gland ofLithobius forficatus formerly considered a strand of lymphatic tissue, be designated “glandula ecdysalis” in accordance with its function. 2. The gl. ecdysalis is a single-layered and irregularly folded epithelium surrounding the gl. mandibularis. It is bounded by its own basement membrane. 3. The cells of the gl. ecdysalis represent podocytes. Their pedicels rest on the basement membrane; the terminal ends are usually connected by diaphragms. Extending between the pedicels are widened intercellular clefts. 4. Along the intercellular clefts membrane vesiculations take place that give rise to coated vesicles. Associated specific tubular structures can transform into vacuoles. In the peripheral cell region only a few mitochondria and cytosomes are found. 5. The nucleus is located in the central cell region; it is surrounded by many golgi complexes. Only in the vicinity of the nucleus is a sparsely developed granular endoplasmic reticulum to be found. 6. With advancing postembryonic development the number of cytosomes increases; some become larger than the nucleus. 7. The moulting cycle is accompanied by changes of fine structure. After the critical phase, single lipid droplets and numerous accumulations of glycogen appear. Golgi complexes, mitochondria, and cytosomes seem to increase in number. 8. After ecdysis, and before the next critical phase sets in, neither lipid droplets nor glycogen can be found. Numerous cells disintegrate, and within the surviving ones vacuoles of varying size appear. 9. The organelles and structures described and their possible functions are compared with similar structures known from the literature.

Notes: Summary Observations made on ponded white spruce wood with the electron microscope revealed that initial branching of perforation hyphae of soft rot fungi did not parallel microfibrillar orientation in the S2 wall layer but rather occurred perpendicular to this alignment. In the absence of structural evidence suggesting mechanical entry it appeared that cell wall pencetration was accomplished through enzymatic activity at the hyphal apex.

Notes: Summary A preparative technique is presented which allows simultaneous examination of the surface and internal ultrastructure of refined and unrefined pulp fibres. Fractured cross sectional surfaces of frozen fibres are replicated and examined by transmission electron microscopy. Possible applications of the procedure to anatomical studies of wood are outlined.

Notes: Summary Wood thermal conductivities (from the literature) are directly related to the electrical properties of the same species (measured by the author) in the density range occurring in nature. The correlation coefficient between permittivity and conductivity was found to be higher than that between conductivity and density for various species of wood. Variation in the chemical components of woods results in variation in the thermal conductivities of woods.

Notes: Summary The angle at which the slip plane traverses the wall of cells subjected to longitudinal compression has been studied in detail and appears to be a function of the angle of the microfibrils in the middle layer of the secondary wall together with the ratio of the modulus of elasticity in the longitudinal and radial planes. These parameters can adequately explain the observed variations in slip plane angle that occurred between species, between early and late wood, and at different temperatures. Significant differences were absent in the comparison of radial and tangential walls, normal and compression wood, and samples at different moisture content.

Notes: Summary Evidence is presented indicating that limits to ultimate tensile strength improvements on thin wood sections by grafting techniques are set by structural rather than chemical factors. For effective tensile strength increase in woods, the strength of which is strongly dependent on individual fiber strength, grafting must be operative on both inter-fiber bonding and intrinsic fiber strength. The requirement is more pronounced in products modified by radiation rather than heat/catalyst means.

Notes: Summary The variation in length of cell elements both in bark and wood of a few tropical trees (Mangifera altissima, Mansonia altissima, Pentacme contorta, Pterocarpus marsupium, Shorea megrosensis, Shorea squamata, Triplochtion scleroxylon) is described. The phloem fibres and sieve tube members show a tendency for increase in length from periderm to cambium, just as the wood fibres and vessel members increase from pith to cambium. The phloem fibres are generally longer than wood fibres (40–70%). In woods with storeyed cambia the sieve tube members exhibit no variation, retaining a constant length throughout the width of the bark; the phloem fibres possess the normal trend of a length increase from periderm to cambium. The length variation of sieve tube members and phloem fibres with the height of the tree generally exhibits a decreasing trend from butt to top, although a slight increase in length of phloem fibres at the top was noticed.

Notes: Summary Douglas-fir and red oak wood meal, cellulose, and an 0-acetyl-4-0-methylglucuronoxylan were exposed to finely divided iron powder under conditions favorable for rusting. Analyses of the wood meal and polysaccharides following exposure indicated that rusting iron causes a decomposition of all wood constituents. Cellulose was oxidized in the presence of rusting iron to form an oxycellulose which was predominantly reducing in character. Direct depolymerization of cellulose and xylan also occurred. The deterioration was favored by an acidic environment, contrary to earlier reports that the primary degradation mechanism is alkalidependent. An iron-catalyzed oxidation of wood constituents is theorized to occur as a result of free-radical production associated with ferrous ion oxidation in the presence of organic compounds. The free radicals produced lead to the formation of hydrogen peroxide which allows Fenton-type reactions to occur.

Notes: Summary The paper is to give a survey on problems of wood preservation, selecting examples of fundamental research as well as of results of applied studies significant for the practice. Needs and trends in research are indicated. The interdisciplinary character of wood preservation science is demonstrated.

Notes: Summary Wet cross-sections up to several centimetres thick of young trees show marked translucency. Various research applications are suggested by the observation of this phenomenon.

Notes: Summary Giant sequoia latewood compression wood (CW) tracheids had pit canals that flared toward the lumen with extended poorly defined inner apertures that paralleled the fibrils in the S2 walls. Boiling and drying of CW and normal wood (NW) blocks induced split extensions at the CW pit aperture grooves but not at the NW pit apertures. These split extensions of the CW pit apertures were present also in longitudinal microsections. The mean fibril angle of 21 to 25 degrees of this well-defined CW was appreciably below the 45 degrees frequently reported. The CW tangential/radial shrinkage ratio of about 1 was distinetly lower than NW (1.6 and 2.1), and appeared to be the result of much lower tangential shrinkage. Both NW and CW specimens when dried quickly in an oven at 100° C had higher shrinkage (long., tang. and rad.) than when air-dried first at lower temperature and higher relative humidity.

Notes: Summary Evidence of the detection by radiography of α-conidendrin and hydroxymatairesinol, major lignans of western hemlock wood, is presented. Advantages of this new technique to wood chemists, as well as implications to wood technologists in terms of erroneous measurement of the specific gravity of unextracted wood by X-ray densitometry, are discussed.

Notes: Summary A mathematical model of the mechanical properties of wood which changes its moisture content is presented. This model was applied to the description of wood swelling pressure across the grain. In addition, changes in swelling pressure of wood subjected to cyclic changes of its moisture content (moistening-drying-moistening), as well as permanent deformation of this wood after each cycle was described with the aid of this model. Good qualitative and quantitative agreement was found between results of the theoretical calculations and experimental data obtained by other investigators.

Notes: Summary The same material was used as in Part I of this study. Fibril angle decreased with age from over 30 degrees to 7 degrees at about age 30. Accelerated growth by fertilization and thinning at about 20 years caused a slight increase in angle but only for a few years. The semilog correlation with age was very high, r=0.96. Tracheid length was highly correlated with fibril angle, r=0.94. Growth rate and percent latewood were minor causes of changes in fibril angle. Extractive content did not change significantly with plot treatment. Lignin percent was highest near the pith and decreased to about age 20; r was-0.94 for the controls using the log of age. Accelerated growth increased lignin compared to the control trees by about 0.7%. Holocellulose and alpha cellulose increased from the pith to about 20 years of age. Accelerated growth caused a small decrease of 0.9% for both constituents during the next 6 years compared to uniform-growth trees, then the differences became much less.

Notes: Summary The viscous and slip flow terms of the Hanks-Weissberg and Petty-Puritch gas flow equations are compared. A Couette correction of 3π/8 x radius must be added to the capillary length in the viscous term of the latter equation. The slip flow terms in the two equations are equivalent to within ±10%. A modified method is presented for calculating the radius and number of short capillaries from gas flow measurements. The applicability of this method was confirmed by measurements of gas flow through artificial membranes containing short capillaries. Earlier published values for the number and radius of pit membrane pores are recalculated using the modified method. The possible effects of very close spacing of pores in a membrane are discussed and it is suggested that the Couette correction is probably still applicable in this case.

Notes: Summary The effects of strain-rate, moisture content, and bulk density on the transverse fracture properties of Pinus radiata wood are described. As the strain-rate is increased from 2×10-6 sec-1 to 102 sec-1, the strengths of both wet and airdry woods increase, with the greater increase occuring in wet wood. At the same time, the failure strain tends to decrease. The energy absorbed by airdry wood decreases, and that absorbed by wet wood increases. An explanation of the variation of strength with strain-rate is developed. Initially the measured strength of latewood is related to the strength of the compound middle lamella matrix connecting adjacent tracheids, and then by making the assumption that wood failure occurs when a certain proportion of the load bearing hydrogen bonds in the matrix have failed, and by applying reaction rate theory to the formation and rupture of the stressed hydrogen bonds, a strength versus time to failure relationship that is in good agreement with the experimental data is derived.

Notes: Abstract Phototaxis by each zoeal stage of the crab Rhithropanopeus harrisii (Gould) was quantitatively measured by means of a microscope closed-circuit television system. The megalopa stage is indifferent to light stimulation and was thus not tested. The action spectrum for positive phototaxis is similar at each zoeal stage, having the most pronounced maximum at about 500 nm and smaller maxima at 400 and 280 nm. Responsiveness to various intensities of 500 nm light is also similar at each stage. After dark-adaptation strongest positive phototaxis occurs at intensities between 1.0 and 3.0x10-4 W/m2, with no negative phototaxis to lower intensities. After light-adaptation, the positive response occurs to higher intensities between 20 and 0.01 W/m2, with a pronounced negative response to lower intensities. Generally, mean swimming speeds during positive phototaxis do not change with stimulation intensity, although during negative phototaxis mean speeds do vary with intensity. At the highest intensities which initiate a negative response, mean values are significantly greater than values for positive phototaxis. Based on the pattern of phototaxis at each developmental stage, a prediction of events during diurnal vertical migration is possible. The negative response after light-adaptation might also function as a shadow reflex.

Notes: Abstract From 18th December, 1968 to 5th January, 1970, zooplankton samples were taken in darkness and using artificial light in selected areas of the Dar es Salaam coast (Tanzania, S. E. Africa). Surface sea temperature was measured on most occasions, salinity for the first 7 months only. The neritic waters of Dar es Salaam experience a warm period during January to March and a cool period during July to September. The annual salinity cycle is not known. Thirtysix “dark” and 17 “light” zooplankton samples were analysed; where possible, organisms were identified to species, others to generic or higher taxonomic level. The principal taxa and their mean percentage proportions (figures in parentheses) in the “dark” samples were: Calanoida (49. 1), Larvacea (11. 9), Corycaeus spp. (6.4), Cypridina sinuosa (5.6), Oithona spp. (4.8), caridean larvae (4.0), Sagitta spp. (3.8), Euterpina (2.1), Lucifer (1.2), Oncea (1.2), calyptopis larvae (1.0), Hydromedusae (1.0), Euconchoecia chierchiae (1.0), Creseis acicula (1.0), brachyuran zoeae (0.8), Ctenophora (0.5), Mysidacea (0.5), fish eggs (0.5), postlarval bivalves (0.5), postlarval gastropods (0.5), Cumacea (0.1), Gammaridea (0.1) and Hyperiidea (0.1). Evadne tergestina and Thalia democratica abound in waters at certain times of the year only and then virtually disappear. The remaining groups were numerically unimportant most of the time. Almost every major group showed an annual cycle of abundance; greater numbers were recorded either for the entire or part of the period February to August, compared to the period September to November. From the end of January to early August, 1969, the average numbers per haul of total zooplankton were about three times greater than for the period mid-August to mid-November. During February-March and July-August, several oceanic indicators were observed together in the neritic waters. Artificial light induced the following changes in night zooplankton: Mysidacea, Leptochela sp., Hyperiidea, Cypridina sinuosa, brachyuran megalopae and fish larvae were attracted towards artificial light and aggregated densely under the lamp; Calanoida, Corycaeus spp., Macrosetella, Microsetella and Euterpina avoided regions of strong illumination and aggregated in dim-lit areas; Lucifer, Creseis acicula and postlarval gastropods were more abundant in dim-lit samples compared to “dark” hauls; caridean larvae, brachyuran zoeae and larvaceans were less abundant in high-intensity “light” samples compared to “dark” hauls on the same nights.

Notes: Abstract Collection and culture of the large lobate ctenophore Mnemiopsis mccradyi Mayer is described, including the requirements for successful development of larvae. Particular attention must be given to the collection of these delicate animals, the handling and provision of live microzooplankton of suitable size for the larvae, and the provision of food densities for the adults which neither stimulate “wasteful” feeding nor limit their growth. Although these ctenophores will ingest detritus and algal cells in high concentration, they lost weight at the same rate as starved individuals unless provided with living zooplankton. Under optimum conditions, specimens would lay eggs within 13 days of their own birth. By the 17th day they laid eggs daily, and had produced an average of 8,000 eggs within 23 days after birth. The maximum number of eggs laid by a single wild individual within 24 h after being brought into the laboratory was 10,000. Their high fecundity, rapid generation time, and ability to self-fertilize help to explain their sudden appearance in bloom proportions at periods of high food concentration in the environment, often referred to in the literature.

Notes: Abstract Species of the copepod genus Calanus frequently dominate the marine zooplankton in boreal and arctic waters. Up to now there have been no operational means of identifying several species closely related to Calanus finmarchicus. Reanalysis of these taxa, using material from plankton samples collected throughout Northern Hemisphere polar and coreal waters, shows that there are 3 sibling species which have been previously combined under the names C. finmarchicus and C. glacialis. Several new taxonomic characters permit unequivocal identification of C. finmarchicus, C. glacialis, and a new species, C. marshallae. Claims that C. finmarchicus and C. glacialis are subspecies are refuted; there is no evidence that the two species continuously intergrade either where they co-occur or where they are allopatric, nor is there evidence that the two species hybridize. C. finmarchicus is basically restricted to the North Atlantic Ocean and C. marshallae to the North Pacific Ocean and Bering Sea; C. glacialis is primarily an Arctic species, but its geographical distribution slightly overlaps those of the other two species. Taxa closely related to C. finmarchicus and C. helgolandicus probably represent two separate, but closely linked evolutionary lineage; species of these two lineages are placed in one of two species groups, the finmarchicus group and the helgolandicus group.

Notes: Abstract The surface “skin” of the ocean is exposed to very particular conditions (ultra-violet irradiation, oxygenation, bubbling), which produce an accumulation of planktonic constituents. Many important parameters were studied in surface and subsurface waters of an inshore area of the North Mediterranean Sea over a period of 1 year. Differences in temperature and salinity between surface and subsurface layers were observed in the summer. Nitrates and phosphates are more abundant in the surface layer before the plankton bloom. Particulate and dissolved organic matter is 2 to 5 times more abundant in the surface than in the subsurface layer. The plankton bloom, very significant in the surface layer, is succeeded by an accumulation of carbohydrates. The surface microlayer of the sea may be considered a valuable indicator of planktonic development in the euphotic layer.

Notes: Abstract The release via exudation of dissolved organic carbon by Ascophyllum nodosum (L.) Le Jol. was investigated under laboratory conditions. In contrast to results previously reported by Sieburth (1969), continuous release of organic matter was found with only 1 specimen out of 21 tested either in stagnant sea water or in sea water flowing through the system. The holdfast of the plants was found to release relatively large amounts of organic material; however, this release lasted only for short periods, and was most probably due to damage caused by removing the plants from their substrate. The possible reasons for the failure to detect exudation are discussed. With Fucus vesiculosus L., no reliable results could be obtained, most probably due to particulate matter sloughing off the plants during the washings and during the experiments under conditions of photosynthesis.

Notes: Abstract The release of dissolved organic carbon (DOC) by Ascophyllum nodosum (L.) Le Jol. and Fucus vesiculusus L. during rehydration was investigated after desiccation under experimental conditions. During 30 min of rehydration of plants which had lost up to 70% of their water, A. nodosum released about 2 to 10 mg C/100 g dry weight, while F. vesiculosus released 10 to 50 times more. When dried to water losses exceeding 70%, plants of both species yielded similar amounts of DOC, approximating 2 g C/100 g dry weight. Considerable variance in the amounts of DOC released by individual plant of both species was observed over the whole range of water losses tested. Among the DOC released, the portion of carbohydrate-C was O to 5% with A. nodosum but 2 to 47% with F. vesiculosus. This difference was most pronounced when less than 100 mg C/100 g dry weight were released. A. nodosum regained a smaller percentage of its original weight than F. vesiculosus after 30 min of rehydration when more than 30% of fresh weight were lost during desiccation. Curves were obtained which enable the estimation of water losses in naturally desiccated specimens within 30 min.

Notes: Abstract A strain of the marine hymenostome ciliate Uronema marinum was isolated in axenic culture. This strain, designated PW2, was cultivated in a chemically defined medium containing 17 amino acids, 4 nucleotides, 5 fatty acids, stigmasterol, 8 growth factors and an artificial sea water. Increased populations were observed when either phosphatidylinositol or Tween 80 were included in the medium. The vitamins thiamine, riboflavin, pyridoxal, nicotinamide, folic acid and pantothenate were required by U. marinum PW2. No requirement could be demonstrated for exogenous thioctic acid or biotin, although growth was diminished in their absence. The amino acid and nucleotide requirements were found to be higher than the levels reported for other ciliates. This strain was found to be euryhaline, with maximum growth observed in media of specific gravity 1.007, corresponding to approximately 25% sea water. Although no requirement could be demonstrated for Fe, Zn, Mn or Cu, high levels of these metals were observed to be toxic. Growth was observed over a pH range of 6.6 to 8.3, with an optimum observed near 7.3.

Notes: Abstract Fourteen crinoid species are found along the coral reefs of the northern Red Sea that form aggregations of different species at various depths. The shallowest aggregation consists partly of Lamprometra klunzingeri and Capillaster multiradiatus, occurring subtidal to a depth of 2 to 5 m. Of this group, Heterometra savignii inhabits depths down to 12–15 m. Further down, another group of 10-armed crinoids occurs, dominated by Decametra chadwicki and Oligometra serripinna. The deepest aggregation of crinoids occurs at 45 m; its most common members are Colobometra arabica and Comaster distinctus. Feeding on micro- and nanoplankton, shallow-water crinoids show a circadian activity rhythm; in deeper aggregations (10 to 12 m), this behaviour changes with decreasing illumination, to a diurnal activity rhythm. The symbiotic animals living on crinoids comprise 27 taxons, among them Copepoda (6 species), Mollusca (2 species), Polychaeta (11 species, especially Myzostomida); Ophiurida (1 species), Crustacea, Decapoda (6 species); and the clingfish Lepadichthys lineatus. These symbiotic animals form food webs at various depths, according to the distribution of their crinoid host. The occurrence of Indo-West Pacific and Mediterranean commensals on the same crinoid in the Gulf of Aqaba is of special interest.

Notes: Abstract Benthic infauna was collected with a 0.2 m2 van Veen grab at 48 stations in Puget Sound, Washington, USA during February–March 1969. All the crustaceans, lamellibranchs, and echinoderms were identified and counted. Particle size distributions and nitrogen contents of the sediments, depths, and temperature and salinity of the bottom water were determined at all stations. The first three factors of a factor analysis applied to between-stations measures of affinity, explained 41.26% of the total variance. The first factor had representative stations on shallow-water mud bottoms, the second factor on bottoms dominated by coarse sediments, and the third factor had representative stations on deep-water mud bottoms. The multiple correlation coefficients for each of the three factors with depth and mean particle size of the sediments were 0.752, 0.897, and 0.706, respectively. The factor analysis did not result in clusters of stations that could be interpreted as discrete benthic communities. The number of species per 0.6 m2 ranged from 8 to 55 species, with a mean of 26.4 species. The frequency distribution of specimens among the species was in good agreement with a log-normal distribution. The number of specimens per 0.6 m2 ranged from 57 to 1733 specimens, with a mean of 584.0 specimens. The species diversity ranged from 0.34 bits/individual to 4.35 bits/individual, and there was a weak trend of increasing diversity towards coarser sediments. The first three factors applied to the matrix of between-species correlation coefficients explained 43.72% of the total variance. With each factor there was one group of species with high positive loadings and one group with high negative loadings. Each group of species could be identified with particular environments. The standing crop, measured as ash-free dry weight, ranged from 0.490 to 54.093 g/m2, with a mean of 13.752 g/m2. Only about 24% of the variability in standing crop could be attributed to variability in sediment types, nitrogen content in the sediments, salinity of the bottom water, and depth.

Notes: Abstract Cores of sedimentary mud, collected on a transect between the Isle of Man and Ireland, were qualitatively analysed for free amino acids by thin-layer chromatography of the dansylated (DNS) derivatives. The DNS derivatives of isoleucine/leucine and α-aminobutyric acid were found in all samples, while the derivatives of phenylalanine, valine, arginine and ammonia were usually present. Acid hydrolysis followed by treatment with ninhydrin showed the presence of peptidyl amino acids in half the DNS-reacted extracts. No distribution pattern of amino acids was found either with geographical location or down the depths of the cores. Attempts to quantify the method were unsuccessful. Other analyses indicated the presence of glucose/galactose, but no neutral or phospholipids or recognizable plant pigments were identified.

Notes: Abstract The growth cycle and related vertical distribution of the thecosomatous pteropod Spiratella (“Limacina”) helicina (Phipps) were studied. S. helicina has a life cycle of approximately 1.5 to 2 years in the central Arctic Ocean (Canada Basin). It spawns mainly during the spring to summer period, and on a small scale during the winter. The young double their sizes during the winter months of October to May, slow down in growth until late summer, and attain maximum size in early winter. The oldest disappear by late March. Gonadal tissue was first seen in young pteropods of 0.7 mm diameter, the predominant size from February to April. S. helicina 0.8 mm in diameter, the size predominant from May through July, are mature and hermaphroditic. Growth during the winter months suggests that particulate organic matter is available during this period to these obligate ciliary feeders. Vertical distribution is size and season-dependent. The youngest specimens collected (0.2 to 0.4 mm) were found concentrated in the first 50 m. The larger sizes dispersed during the summer months, and tended to concentrate in the top 150 m during the rest of the year. They aggregated in the top 50 m from late winter through early spring, and fall through early winter; then concentrated in the 100 to 50 m level until the end of winter. Numerous environmental factors seem to be involved in determining the vertical distribution of the species in the central Arctic Ocean.

Notes: Abstract The dynamic quantitative balance between prey and predator invertebrate species inhabiting the same shallow-shelf (sublittoral level bottom) benthic communities was first discussed by Thorson (1953). Thorson considered the exact timing of larval settlement of prey and predator species possessing pelagic development and temporal supression of the adult predators' feeding activities during reproduction at the time of the preys' settlement to constitute the major factors which facilitate survival of the prey species in such communities. However, information obtained demonstrates that Thorson's “mechanism of balance between predator and prey species of benthic communities” is not always effective in securing survival from predation not only of the prey's spat but even sometimes of the predator's spat also. Because of this, the “mechanism” can not be rated as universally effective in all situations. Analysis of the data so far published demonstrates that, in marine benthic communities, especially in shallow-shelf waters, it is not uncommon for gametes, larvae, or early juveniles of different prey species to pass alive through suspension (filter)-feeding and deposit-feeding adult invertebrates preying on them. Sometimes development can even continue after excretion by predators. The hypothesis of Voskresensky (1948) and Goycher (1949) of the importance of this phenomenon for the maintenance and recruitment of the mussel Mytilus edulis and other filter-feeding lamellibranchs of nearshore waters preying on their own and other lamellibranch pelagic larvae must be rejected on the basis of accumulated data on their feeding and general biology and on the adverse influence of the mucous of their faecal pellets and pseudofaeces on the larvae excreted by them alive. The data considered here demonstrate that, although the passing alive of larvae and spat of benthic invertebrates through benthic predators is not uncommon in shallow-shelf bottom-communities, it plays no important role in the processes of maintenance and recruitment of the species and communities involved nor of the marine benthos as a whole. The actual ecological significance of predation on pelagic larvae and bottom spat of benthic invertebrate prey species by all three main trophic groups of marine benthos (suspension or filter-feeders, deposit-feeders, carnivores) and its importance to predator-prey dynamics in marine benthic communities remains open to debate until more reliable quantitative data become available.

Notes: Abstract Average radial growth rates of the hemispherical aragonite colonies deposited by the Indo-Pacific scleractinian reef coral Platygyra spp. were determined by measuring the thickness of density variations in the skeleton that are revealed by X-radiography. Ninety-one specimens from 21 localities were examined, but only 54 of these exhibited well-defined growth-banding. The apparent temperature dependence of growth rate is linear over the range 23.9° to 29.3°C, averaging 5.4±0.94 mm/year at 24°C, 8.0±0.42 mm/year at 27°C, and 9.7 ±0.58 mm/year at 29°C (90% confidence limits). Expression of the influence of temperature on growth rate in terms of the Arrhenius equation yields an activation energy of 20,680 cal/mole, which is comparable to values for typical biological reactions, but is only half that reported for skeletogenesis in another reef coral, Pocillopora damicornis, on the basis of controlled incubation studies involving 45Ca uptake.

Notes: Abstract The symbiotic pearlfish Carapus bermudensis (Jones) demonstrates the ability, as an adult, to relocate the host sea cucumber Actinopyga agassizi in the laboratory. Host location behavior is effected unimodally with chemically mediated information of host orgin. Positive orientation of pearlfish to host “odor” does not involve chemically-elicited rheotaxis.

Notes: Abstract Germanic acid was shown to inhibit photosynthetic 14CO2 uptake in marine diatoms. Inhibition was not complete even at concentrations of 20 mg Ge/1 nor in cultures incubated for extended periods of time (up to 24 h). The decrease in photosynthesis due to Ge(OH)4 was independent of the stage of growth of the diatom culture. At 0.5 and 1.0 mg Ge/1, the degree of inhibition was dependent on the concentration of Si(OH)4 in the medium. At 5 and 10 mg Ge/1, inhibition was not affected by Si(OH)4 concentrations as high as those found in the sea-120 μg-at Si/1. The effect of Ge(OH)4 on photosynthesis is specific for diatoms; other marine phytoplankton were not inhibited. In mixed cultures of diatoms and marine flagellates, the reduction in 14CO2 fixation upon addition of Ge(OH)4 was used to calculated the proportion of diatom photosynthesis to total photosynthesis, and calculated proportions agreed well with actual proportions. Inhibition by Ge(OH)4 was also used to estimate the percent of diatom photosynthesis in a natural marine community, and this was compared with the diatom portion of the crop. Diatom photosynthesis was higher than one might expect from crop figures, although both diatom photosynthesis and diatom numbers in the crop were low.

Notes: Abstract The antheridium development of Sargassum micracanthum Yendo and S. ringgoldianum Harvey was investigated with the iron-alum haematoxylin staining method and the aceto-carmine squash technique. Synapsis occurred at the prophase in the first division while the chromatin threads were still contracted, and the nucleus passed through diakinesis. The first two divisions in the antheridium were meiotic, and the four other divisions (mitosis) followed without cytokinesis. In S. micracanthum and S. ringgoldianum, 31 and 32 chromosomes respectively were counted at prometaphase in the first division, 64 sperm nuclei were organized in the final division. After the final division cytoplasmic cleavage occurred, and 64 sperm cells were finally completed in an antheridium. Centrosomes and asters could not be discerned at any of the divisions, because of limited magnification facilities. A peculiarly shaped small body was observed at the prophase of the first division, but not thereafter.

Notes: Abstract Two behavioral defenses of the slipper shell Crepidula fornicata (L.) against attack by the oyster drill Urosalpinx cinerea (Say) are described: (1) Jabbing: when an oyster drill approaches, the slipper shell lifts the edge of its shell, extends the head and, with the radula, pricks or rasps the foot of the predator, which instantly retracts into its shell; sometimes, after repeated approaches, the oyster drill moves away. (2) Pivoting: when an oyster drill mounts C. fornicata, the latter slowly and repeatedly rotates its shell in a horizontal plane at a constant rate and through a constant arc. If this action brings the predator's shell to bear against an obstacle, motion ceases and C. fornicata maintains the pressure until the oyster drill is dislodged. These aggressive tactics are adaptive defensive measures for a nearly sessile prey otherwise highly vulnerable to oysterdrill attack.

Notes: Abstract The larval development of Cancer anthonyi Rathbun (Decapoda, Brachyura) is described from laboratory rearing experiments. The external anatomy of the various larval stages is illustrated. A prezoeal stage, 5 zoeal stages and 1 megalopa stage were identified. At 17.5°C it took an average of 32.5 days for the first-stage zoeae to develop through the fifth zoeal stage and molt to the megalopa stage. The general internal anatomy of C. anthonyi larvae is discussed, and a drawing of a parasagittal section of a megalopa-stage larva is included.

Notes: Abstract Variability and dominance of Euphausia superba Dana larval forms (Furcilia-I and Furcilia-II stages) in the plankton of the Scotia and Weddell Seas have been investigated. New forms (1′, 2″, 3″ and 1″4′) have been recorded. The dominant forms of Furcilia-I stage are proposed to represent the initial dominants. In accordance with the initial dominance, five types of larval form combinations have been established. During the initial dominance change — from 5′ to 2′, the larval form number increases. This phenomenon is due to parallel development of euphauiid larvae; it results from a developmental pathway change in the main larval mass. Such deviations are reflected in an initial dominance change. In each pathway, the larvae pass through an unequal number of moults before reaching Form 5″ (in accordance with the proposed moult scheme of Furcilia-I stage larvae). In the case of initial dominance of less-developed forms, the presence of different parallel pathways increases. As a result, the total number of larval forms present in the plankton changes, causing increased variability of the total number of larval forms. Each type of larval form combination is the result of summation of all larval forms, which derive from different developmental pathways of the larvae in different localities. The most usual developmental pathway for Euphausia superba is through Form 5′, which may, thus, be regarded as the main developmental pathway for this species. This pathway probably corresponds to optimal environment conditions for larval growth and morphogenesis with maximal synchronisation of both processes. Consequently, it may be suggested that changes in developmental pathways of larvae are connected with suboptimal environmental conditions.

Notes: Abstract Photosynthesis in whole plants of Chondrus crispus Stackhouse was measured by 14C uptake under various light intensities and temperature regimes. In plants collected from waters of 6° to 7°C, photosynthesis did not increase with light intensity over a range of 200 to 2400 foot candles (ft-c). However, in plants collected from waters of 10° to 12°C, the rate of photosynthesis was lower over the range 200 to 1400 ft-c but, at 2000 ft-c, increased to a level similar to that of the 6° to 7°C plants. Ethanol-soluble and insoluble fractions showed similar patterns.

Notes: Abstract The composition and seasonality of the benthic algae of the Florida Middle Ground, an offshore area of extensive reef outcroppings, 25 to 60 m deep in the eastern Gulf of Mexico, are described. Collections and observations were made by SCUBA diving during June, July, and September, 1971, and January 1972. Ninety-one algal species (92 taxa) were obtained, including 6 species newly reported for Florida and the eastern Gulf of Mexico. The flora is predominantly tropical, with Caribbean affinities. Marked seasonal differences in species diversity and abundance were present. An extensive or well-anchored holdfast system was a common feature of those species which appeared to be perennial.

Notes: Abstract Flux of the heavy metal cadmium through the euphausiid Meganyctiphanes norvegica was examined. Radiotracer experiments showed that cadmium can be accumulated either directly from water or through the food chain. When comparing equilibrium cadmium concentration factors based on stable element measurements with those obtained from radiotracer experiments, it is evident that exchange between cadmium in the water and that in euphausiid tissue is a relatively slow process, indicating that, in the long term, ingestion of cadmium will probably be the more important route for the accumulation of this metal. Approximately 10% of cadmium ingested by euphausiids was incorporated into internal tissues when the food source was radioactive Artemia. After 1 month cadmium, accumulated directly from water, was found to be most concentrated in the viscera with lesser amounts in eyes, exoskeleton and muscle, respectively. Use of a simple model, based on the assumption that cadmium taken in by the organism must equal cadmium released plus that accumulated in tissue, allowed assessment of the relative importance of various metabolic parameters in controlling the cadmium flux through euphausiids. Fecal pellets, due to their relatively high rate of production and high cadmium content, accounted for 84% of the total cadmium flux through M. norvegica. Comparisons of stable cadmium concentrations in natural euphausiid food and the organism's resultant fecal pellets indicate that the cadmium concentration in ingested material was increased nearly 5-fold during its passage through the euphausiid. From comparisons of all routes by which cadmium can be released from M. norvegica to the water column, it is concluded that fecal pellet deposition represents the principal mechanism effecting the downward vertical transport of cadmium by this species.

Notes: Abstract Water, ash, C, H, N, lipid, carbohydrate, chitin and protein contents were determined for 28 species of midwater crustaceans. Variation of these components as a function of depth of occurrence, relative buouancy and respiratory rate of these species was examined. Vertical distribution data for 10 of the species based on discrete depth crawls is provided. The relative bouyancies of 16 of these species were measured. The caloric contents of 21 species were calculated. Lipid content (percent wet weight) and caloric density increased at intermediate depths, but apparently decreased at the greatest depths; it is suggested that this decrease is related to the relatively large size of these organisms and the energy limiting conditions in the deep-sea. Protein content (percent wet weight) decreases with increasing depth of occurrence, and is apparently related to a substantial fraction of the decrease in respiratory rate with increasing depth of occurrence in these species. Within the range of values examined, relative buoyancy appeas to be independent of metabolic rate. It is, therefore, suggested that the energy involved in maintaining an animal in the water column is generally insignificant compared to its overall activity. Furthermory, advantages of neutral buoyancy other than energy conservation may be more important selective factors for this characteristic.

Notes: Abstract The rates of sedimentation of organic detritus were measured at 3 stations in two Scottish sea lochs, Loch Etive and Loch Creran, using sedimentation jars exposed at various depths. Details are given of the seasonal and depth distribution of sedimenting material, and its composition for a 1-year period. Differences in the pattern of sedimenting material collected at different depths and in the seasonal patterns of sedimentation at the different stations suggested that, in each case there were differences in the relative importance of detritus from various sources. At all stations, phytoplankton production made a relatively small contribution to the total detritus collected, either directly as dead cells, or indirectly as the faeces of zooplankton organisms. Near the head of Loch Etive there were contributions by filamentous algae and Enteromorpha sp., but a major source of detritus was terrestrial debris, mainly carried into the loch in the waters of the River Etive. In the lower basin of Loch Etive, terrestrial detritus also contributed to the total sedimenting near the surface, but at greater depths much of the material collected in the sedimentation jars probably resulted from short-term resuspension and re-deposition of bottom material, reflecting a net transport of fine sediment from the shallower to the deeper areas of the loch. Secondarily resuspended material was also a major source of material collected in the jars exposed in Loch Creran.

Notes: Abstract Axial skeletons of two closely related, sympatric species of gorgonians were examined for details of gross morphology, internal organization and fine structure. Banded fibers with a periodicity of 430 Å and oriented circum-axially to the longitudinal axis of the skeleton (i.e., lying on the plane perpendicular to the axis), were revealed by electron microscopy in the axial skeleton of Muricea californica; they indicate the presence of a collagen-like protein in the gorgoin of this species. No circum-axial fibers were found in the axial skeleton of M. fruticosa. Differences in fine structure are related to gross morphological differences in the skeletons. A sequence of events for the addition of new material to the axial skeleton (growth) is described based on histological observation. Iodine-125 is used as a tracer for the deposition of new skeletal material, and is suggested as a new method for studying gorgonian growth rates.

Notes: Abstract A female blue-ringed octopus, Hapalochlaena sp. (probably lunulata), was maintained in an aqarium for nearly 3 months, during which time it spawned and cared for the eggs until hatching. The young are planktonic. Embryonic development does not differ markedly from that observed in other octopods, uniting certain features of the development of Octopus vulgaris and Eledone cirrosa. In terms of reproductive biology and development, the species differs from the lesser blue-ringed octopus Hapalochlaena maculosa in its mode of spawning, egg size and mode of life of its young. These differences correspond to conditions recorded for Octopus spp. and Eledone spp.

Notes: Abstract Six developmental stages of the bay mussel Mutilus edulis, from fertilization to 32 h after fertilization, and also unfertilized eggs, were exposed for 1 h to different concentrations of the insecticide Sevin and its first hydrolytic product, 1-naphthol. After exposure, the larvae or eggs were separated from the pesticide solution and returned to clean water. At 48 h after fertilization, the numbers of normal and abnormal larvae were determined and 1-h EC50 values (the effective concentrations that caused anomalous development of 50% of the test animals) were calculated. The most sensitive developmental stage was the one that occurred shortly after fertilization at the time of appearance of the first polar body. Thereafter, sensitivity decreased as age increased. The EC50 of Sevin for the first polar body stage and 32-h stage were 5.3 and 24.0 mg/l of Sevin, respectively. The EC50 of l-naphthol for the first polar body stage was 5.2 mg/l. Effects of the toxicants on development were characterized by disjunction of blastomeres, a reduction in the rate of development, and asynchronous and unaligned cleavages.

Notes: Abstract Several aspects of buoyancy were studied in the normally pelagic eggs of the sciaenid fish Bairdiella icistia (Jordan and Gilbert). Spawning fish acclimated to a low salinity (15‰) produced larger, more buoyant eggs which had a higher water content than eggs produced by fish living in ordinary sea water (33‰ S). Eggs fertilized in lower salinities were larger and more buoyant than eggs fertilized in higher salinities. The salinity of the medium during the first 5 to 7 min after fertilization had a lasting effect on egg buoyancy, but subsequent transfer to a different salinity also influenced buoyancy. Although egg buoyancy in this species can be influenced by the ambient salinity both before and after spawning, the capacity for adjusting buoyancy is limited, and eggs spawned in salinities lower than 30‰ would probably sink.

Notes: Abstract The morphology of the eyes of 3 salariin Blenniidae have been investigated and compared: Salarias fasciatus (inhabiting the sublittoral), Istiblennius edentulus (eulittoral), and Alticus kirkii (supralittoral). An effective protection against desiccation in A. kirkii is offered by the very thick cornea conjunctiva. Extension of the visual field in this species is achieved by protrusion of the eyes from the head, by recession of the dermal pigment, and by a relatively large lense which allows better perception of marginal rays. The retina of I. edentulus is adapted for amphibious vision by the existence of many prominent swellings and folds, and of a central depression into which the lens can be with-drawn. Thereby, the stronger rays of light retraction present on land are focussed on the swellings, since the retina of the depression is under-developed. The cornea conjunctiva and propria of A. kirkii are separated, and thereby constitute an additional eye chamber. Presumably this cavity possesses a lower refractive index than the cornea or water, and thereby enables sharp vision in air, since the light-concentrating effect of the curved cornea is thus diminished. Additionally, the shape of the cornea propria can be varied, since it is centrally connected with the lens; by this means the eye chamber can be extended, enabling displacement of the tocal point of the light rays to correspond with the momentary residence. The adaptations described here for I. edentulus and for A. kirkii have so far not been reported in other amphibious vertebrates.

Notes: Abstract Seawater, when equilibrated with a sample of No. 2 fuel oil, becomes toxic in varying degrees to growth of representative types of microalgae, two blue-greens, a diatom, two greens, and a dinoflagellate. For a sensitive organism such as Thalassiosira pseudonana, Strain 3H, 5 ml of seawater equilibrated with fuel oil (containing 15 mg/l of organics) in 20 ml of growth medium is lethal, or roughly in the range of 40 to 400 ppb if the toxic material(s) constitute 1 to 10% water also immediately stops photosynthesis in organism 3H. For other microalgae tested e.g. 580 (a green alga) and PR-6 (a blue-green alga), similar effects on growth and photosynthesis were found, but required higher concentrations of the oil-equilibrated seawater. Water solubles from Kuwait or Southern Louisiana crude oils (when the straight crude oil was equilibrated 1:8 with seawater) were not toxic; however, specific fractions obtained by distillation did show some water-soluble toxicity. Growth experimetns in open or closed growth systems revealed that most organisms were inhibited by varying amounts of these two crude oils when in direct contact with them. Organism 580 would not grow above 5 μl of Southern Louisiana/25 ml of medium, or 10 μl of Kuwait/25 ml of medium (oil in direct contact with algae). With both the seawater equilibrated with fuel oil and the crude oils, the toxic activity is mainly localized in medium and higher boiling fractions derived from distillation cuts from these materials.

Notes: Abstract Diurnal changes in abundance caused by vertical migrations have been examined in populations of copepods, ostracods, euphausiids, amphipods, decapods, chaetognaths, siphonophores and fish. The animals were taken in a series of hauls made over a 24 h period with an opening-closing midwater trawl system (RMT 1+8), consisting of a net of 1 m2 mouth area combined in the same frame as one of 8 m2 mouth area. The samples were taken at 250 m depth in a position 30°N; 23°W on 7/8 April 1972. The specific composition of the community and the numbers of individuals changed continuously with time. The numbers of fish, decapods and chaetognaths increased at night, but those of copepods, ostracods and euphausiids decreased. More species of fish, decapods and copepods were present by night than by day, whereas the numbers of species per haul for other groups remained fairly constant. The relative abundances of groups caught by the RMT 1 have been analysed, but similar treatment of the RMT 8 samples was impossible as only 3 groups were taken from this net. Non-migrants were a minority in every group except chaetognaths. Migrant species have been put into one of 6 transitory categories according to their patterns of abundance and hence migrations. Within each category, migratory behaviour varied both inter- and intraspecifically. The patterns of abundance of many species were smooth and continuous, suggesting slow migratory cycles of small amplitude. Conversely, extensive migrants had discontinuous patterns and presumably more rapid movements. Few migrants had a steady numerical plateau between their upward and downward migrations, and most apparently moved up or down continuously. The presence of migratory species in the sampled layer depended upon the time of day or night. It is concluded that, in a vertical series of hauls, the depths of occurrence of migrants will vary with the sampling time. Further-more, a vertical series will show a species minimum migration range but not necessarily its maximum. Individuals of some species were out of phase with the migrations of their main populations. There is evidence that the distributions and migrations of some species of decapods, euphausiids, copepods and fish could be related to the distribution of underwater light. Three pairs of congeneric copepod species were both spatially and temporally segregated for at least part of their diurnal cycles. Such an orderly arrangement could provide a means of reducing competition between species. Some species, however, overtook others on their migrations and the pattern of underwater light cannot, therefore, regulate the distribution of all species in the same way.

Notes: Abstract Submarine sedimentary substrates have been exposed in a new-style special arrangement for benthic colonization. The experiment has been running for 2 years and is planned to continue as a long-term test for several more years, with the purpose of studying independently both the effects of hydrographic and biotic factors as well as those of substrate type. This is accomplished by 3 floating platforms. Each carries 3 open containers filled with clayey mud, sand, and gravel (70 cm diameter, 25 cm deep). The platforms are anchored close together at 11, 15 and 19 m water depths. Their distances from the sea floor vary between 5.5 and 2.0 m. The sediments were obtained from sand pits on land. Substrate samples are continuously taken by divers. Hydrographic data are available by direct measurements from a ship and automatic sensors. The characteristic sources of error of the experiment seem to exert no decisive influence on the benthic production data.

Notes: Abstract A model was developed for use in simulating effects of short-term wind-mixing of the water column on estuarine phytoplankton dynamics. Simulation results, using parameter values estimated from field data, exhibited maxima observed in phytoplankton standing crop over a summer in Auke Bay, Alaska. Short-term wind-mixing of the water column can be important in determining the time of occurrence of phytoplankton community productivity pulses in deep estuaries.

Notes: Abstract Near Santa Barbara, California (USA), the large laminarian kelp Egregia laevigata (Setchell) occurred from the lower intertidal zone to subtidal depths. In the intertidal zone there was a large recruitment of E. laevigata in the spring. The kelp were largely excluded from a zone in the lowest intertidal zone where the surf grass Phyllospadix sp, grew, but were abundant on all other rock surfaces. Experiments demonstrated that, while neither grazers nor sessile organisms significantly reduced recruitment, E. laevigata of the previous year-class did so. There were also interactions among E. laevigata of the same year-class, expressed as a density-dependent mortality of very small algae, and as faster growth rates and greater number of branches of kelp at low densities. These processes tended to make both numbers and biomass of E. laevigata uniform. The mortality rates of large E. laevigata were so high that, in some locations, no kelp survived for more than 8 months. E. laevigata was, therefore, essentially an annual and opportunistic species in the intertidal zone.

Notes: Abstract In order to examine the effects of artificial diets at the tissue level, plaice (Pleuronectes platessa L.) were fed either high (50%) or low (20%) protein diets for several weeks and the total quantities of deoxyribonucleic acid (DNA), ribonucleic acid (RNA), protein and phospholipid in their livers were measured. Alanine amino-transferase, aspartate aminotransferase, glutamate dehydrogenase and glucose-6-phosphatase activities in the livers were also measured. Similar measurements were made on the livers of wild plaice. The total amount of DNA in the livers of both cultured and wild plaice, of standard weight, did not differ significantly, irrespective of dietary history. In fish of standard weight, total hepatic RNA, protein and phospholipid levels were highest in the cultured fish fed high protein diet and lowest in the wild fish. These differences were related to dietary protein supply and environmental temperature. The total organ levels of the liver enzymes in plaice of equal weight were not significantly different in the cultured fish fed high and low protein diets. Wild-fish livers contained a smaller total amount of alanine aminotransferase, aspartate aminotransferase and glucose-6-phosphatase activity than did those of cultured fish. Total liver glutamate dehydrogenase activity was not significantly different in any of the fish examined. It is suggested that kinetic and allosteric factors may be more important in controlling protein metabolism and amino acid cat abolism in fish than total enzyme level.

Notes: Abstract Twenty isolations of marine higher fungi were examined in regard to their cellulolytic capabilities. Application of the viscosimetric method produced detailed information on the cellulolytic activities of marine fungi. However, only the C x -component of the total cellulase-complex could be estimated by this method. The most active species were Dendryphiella salina, Chaetomium ramipilosum, Asteromyces cruciatus and Humicola alopallonella. Only very slight or no C x -activity was observed in Cirrenalia macrocephala, Monodictys pelagica and Zalerion maritimum. This finding reveals no correlation between the cellulolytic activity of the fungi in vitro and their frequency on wood-substrates in situ. For example, differences in the intensity of C x -cellulase production of D. salina are caused by variations in salinity and composition of the nutrient broth, especially by the kind of cellulose added for enzyme induction and by the addition or absence of glucose. Most of the C x -cellulase produced is present in the cell-free culture-filtrate. Only a small quantity is absorbed by the cellulose particles or the fungal mycelia. Parallel to the mycelial growth, and accompanied by a shift in pH, the C x -cellulase-activity rises continuously, attaining a maximum after several weeks. During further cultivation, the maximum remains more or less constant for a long period. Tests using different methods, e.g. cellulose-powder-agarplates, proved unsuitable because of spreading hyphal growth, dark pigmentation, heavy sexual or asexual sporulation and relatively low cellulase production during short culture periods.

Notes: Abstract Nine metals were analysed in whole specimens of the decapod crustancean Cancer irroratus, and three in the exoskeleton of Carcinus maenas. In terms of concentrations (expressed as parts per millions) and concentration factors, 2 groups of metals could be distinguished in Cancer irroratus: Zn, Cu, Fe and Mn in one group, Ca, Mg, Sr, Na and K in the other group. Na excepted, all the metals had concentration factors significantly higher (P〈0.01) than 1. The concentration factor of Na was significantly lower (P〈0.01) than 1, demonstrating the existence in C. irroratus of a barrier to the movement of Na into the crustacean from its environment. Studies of coefficients of discrimination (D), in C. irroratus, for metals considered in pairs, showed, in each case that D was significantly different (Plt;0.01) from 1. Only the discrimination factor between, Zn and Mn was less significantly different (0.05lt;Plt;0.1) from 1. Correlations were made between the concentrations of metals and other parameters: water content, size, and ash content. Significant correlations were found, especially in the cases of the pairs Ca−Sr, Na−K, Cu−Zn, and Mn-animal size.

Notes: Abstract Growth studies of Gymnodinium breve in nutrient enriched and unenriched medium showed that anionic surfactants have the most deleterious effects on initial response, growth rate, and maximum cell numbers as compared with cationic and non-ionics. Degradation rates were determined, and the surfactant with the most favorable rate (C12 alkyl-benzene sulfonate) was further tested. The growth constant, K e , and maximum cell number, N max , decreased with increasing amount of surfactant added to G. breve cultures (enriched sea-water media); a minimum was observed at 12.5 ppb. Above this concentration the values of K e and N max increased to approach control values. This profile was ascribed to the formation of surfactant micelles that are ineffective. The surfactant produced mortality of G. breve (90% mortality versus 12% in untreated samples) in natural red-tide samples, but other algae and zooplankton were undisturbed.

Notes: Abstract Employing the technique of pressure fixation, the effect of high hydrostatic pressure (1 to 800 atm) at 5°C has been investigated on cilia of the gill epithelium in Modiolus modiolus, Mytilus edulis (Baltic and North Seas), and on the skin and muscle cells of Branchiostoma lanceolatum (Pallas). With increasing pressure, the filaments and tubuli are increasingly disorganized to an electron-dense material, which seems to be a conglomeration of the globular structure units. Minimum pressure causing disintegration of filaments and tubules is 300 atm; 600 atm is critical, especially for filaments in skin cells of B. lanceolatum. Whereas the filaments do not show any intermediate stages of damage at any one pressure, microtubules show different stages of disorganization. There seems to be a direct relation between motility and structural organization of cilia. Probably the mechanisms of disintegration of filaments and microtubules are related to the enzymatic activities and the protein-protein-interactions of the subunits. The difference between di-and monomer enzymatic systems in the structures may be important for pressure resistance of the organelles.

Notes: Abstract The shell composition of 5 species of barnacles [Balanus balanoides (L.), B. crenatus Bruguière, B. hameri Ascanius, Elminius modestus Darwin and Chthamalus stellatus (Poli)] collected from four different sites on the coast of North Wales and one site in the Irish Sea were studied using chemical, X-ray diffraction and electron-microprobe analyses. All the shells consisted of calcite. The trace substances studied were Mg, Sr, Na, Mn, PO4, and SO4. Other trace elements detected included Si, Li, Ba, Zn, Cl, and Al. For each species, Mn was the only element in the shell which varied significantly from one locality to another. Variation of concentration of Mn in the shells may be related to the variations of the concentration of Mn in the water, since concentrations in the shells were highest in (estuarine) waters containing high concentrations of Mn. In Balanus balanoides L. and Elminius modestus Darwin, the Mn:Ca and Mg:Ca ratios decreased with decreasing shore level and Sr:Ca varied in the opposite direction. When B. crenatus Bruguière, a subtidal and lower littoral species, and B. hameri Ascanius, a Continental-Shelf species, were compared with the intertidal, species B. balanoides and E. modestus, the Mn:Ca and Mg:Ca ratios followed the same decreasing trend, and the Sr:Ca ratios the same increasing trend with increasing depth. These variations may be related either to increased growth rate of the shells of each species or maxium temperature to which the species is exposed, or both. The differences between species are more consistently reflected, in the concentration of Mn. However, since the concentration, of Mn is correlated with the amount of organic matter in the shell, the specific variations may reflect only the variations in the amount of organic material in the shell of each species.

Notes: Abstract A simple system of shadow cinematography, consisting of a small tungsten halogen lamp, 2 large biconvex lenses and a 16 mm camera, is described for recording the swimming and feeding behaviour of larval fish. The system can be used either with infra-red film to record swimming behaviour independently of ambient light intensity, or with high-resolution film to record food organisms and feeding behaviour. Small plankton organisms of 0.2 mm width can be resolved using high-resolution film. The technique has been used to record the behaviour of plaice larvae (Pleuronectes platessa L.) feeding on the nauplii of Artemia salina L. The perceptive field of the larvae extends to approximately ±60° in azimuth, ±40° in elevation and 1.5 body lengths in range.

Notes: Abstract Cadmium binding proteins have been isolated from liver homogenates of marine vertebrates by ultracentri fugation and gel filtration. Liver samples of the Atlantic grey seal Halichoerus grypus and the Pacific fur seal Callorhinus ursinus contain measurable quantities of cadmium binding protein. The copper rock fish Sebastodes caurinus showed an increase in hepatic cadmium binding protein on administration of CdCl2, in agreement with the known inducible nature of the protein isolated from terrestrial animals. The apparent molecular weights of the isolated proteins were 9000 for the grey seal, 10,000 for the fur seal, and 11,000 for the copper rock fish, as determined by gel filtration.

Notes: Abstract Three Caribbean ascidians were sampled from April, 1972 until June, 1973 and the breeding season determined by the presence of larvae in the colonies. In Eudistoma sp. A, larvae occurred from early June until mid-November, in Trididemnum solidum from mid-June until the end of December, and in Didemnum sp. C, throughout the year with occasional interruptions.

Notes: Abstract From July, 1972 to February, 1973, meiofauna samples were taken from submerged platforms. Substrates were gravel, fine sand, and clayey mud. The individual samples consisted of 20 cm2 ≜ 100 cm3. A diver collected the samples by hand. Some days after submersion of the platforms, colonization by meiofauna began. The submerged substrates were colonized almost exclusively by nematodes and harpacticoids; gastrotrichs were never present. In general, the harpacticoid fauna can be classified into two groups: the first, confined to the mesopsammon, did not colonize the platforms; the second, not limited to the interstitial habitat, did colonize. Two harpacticoid species, Ameira parvula and Danielssenia typica, were markedly dominant. The main migration route to the submerged platform was up the securing lines.

Notes: Abstract Two traps baited with fish were placed on the bottom (5720 m) of the central North Pacific Gyre. A total of 1793 lyssianassid amphipods were collected no ovigerous females and no identifiable males were caught. Five amphipod species were represented [1 undescribed species of Orchomene; 2 undescribed species of Paralicella; Eurythenes gryllus (Lichtenstein); and Cyclocaris sp.], 2 by single specimens. Amphipod samples give no evidence of size-classes. Evidence for scavenging as the amphipods' primary mode of existence is discussed. Forty-four copepods, of a single harpacticoid genus (Tisbella), were also collected.

Notes: Abstract The diel vertical migration of copepods from intermdiate water layers of the Tyrrhenian and Adtiatic Seas has been studied on the basis of plankton samples made from depths down to 1000 m, with a Nansen net, mesh size 250 μ, diameter 113 cm. The species considered display two different patterns of migration: (1) nocturnal ascent, e.g. Pleuromamma abdominalis and Euchaeta acuta; (2) nocturnal descent, e.g. species of the genera Spinocalanus, Scaphocalanus, Temoropia, Mormonilla and Oncaea. These two patterns are compared on the pasis of the dimensions of the species and of their different capacities for active movement. Ililumination is considered to be the most important factor influencing vertical movements. The behaviour of Pleuromamma gracilis is also described, the adult population of which is divided in two discrete sections, each one showing a different pattern of migration.

Notes: Abstract Rates of filtration and digestion of 4 species of ascidians (Clavelina lepadiformis), Müller, Ciona intestinalis (Linné, 1767), Halocynthia papillosa (Linné, 1767) and Microcosmus sabatieri (Roule, 1885) from a rocky shore at banyuls-sur-Mer, France have been studied using the unicellular algae Monochrysis lutheri as food and the methods previously applied to Phallusia mammillata (Fiala-Médioni, 1973). Eleven experiments of 24 h each were performed under constant conditions of temperature, pH, salinity, oxygen and food concentration. No recognizable feeding rhythm emerged; filtration is irregular, varying around a mean value. Observed filtration rates averaged 2489 ml/h/g organ dry weight in Clavelina lepadiformis, 3515 in Ciona intestinalis, 6349 in Halocynthia papillosa and 6909 in Microcosmus sabatieri. The higher rates are related to larger size and higher complexity of the gills. No pseudo-faeces are formed; a very small part of the faecal material is discharged within 24 h. The mean rates of digestion, in mg albumin equivalent/24 h/g organ dry weight, are: Clavelina lepadiformis, 3.05 mg; Ciona intestinalis, 4.74 mg; Halocynthia papillosa, 9.25 mg; Microcosmus sabatieri, 10.41 mg. The amount of digested algae corresponds to 83–92% (mean=85%) of algae filtered. This high percentage indicates good assimilation of Monochrysis lutheri by ascidians.

Notes: Abstract Four oil dispersants of interest for practical use in the Baltic Sea were tested as regards toxicity to animals from the littoral zone of the same area. The dispersants tested were Corexit 7664, Berol TL-188, Berol TL-198, all water-base dispersants, and BP 1100-X, an oil-base dispersant. Two species of fish, two species of bivalves and two species of crustaceans were tested. Significant differences in toxicity were found between the water-base dispersants at concentrations above 1700 ppm. Below this concentration there were no significant differences. The dispersants contain similar surfactants in similar concentrations, but differ with respect to types and amount of solvent. The observed differences at high concentrations are, therefore, argued to be connected chiefly to differences between these solvents. Differences in toxicity to different animal types were found between the water-base dispersants and the oil-base dispersants. The toxicity of Corexit 7664 was (96h LC50 approximate values): fish, 1000 ppm; bivalves, 2000 ppm; crustaceans, 10,000 ppm. The toxicity order was strikingly reversed for BP 1100-X: crustanceans, 150 ppm; bivalves, 2000 ppm; fish, 10,000 ppm. This difference in toxicity for different animal types is suggested to be connected mainly to differences in the chemical character of the outer layer of the body surface of the animals.

Notes: Abstract A single application of 100 parts per billion Sevin in seawater caused disruption of schooling behavior of Menidia menidia in an artificial setting. Although the change, primarily a spreading out of the school over a larger area, was observed after 24 h exposure, placing the fish in clean water did not bring about a return of normal schooling patterns until 72 h. This is attributed to the accumulation of 1-naphthol, a toxic product of hydrolysis of Sevin. The adaptive significance of changes in schooling behavior is discussed.

Notes: Abstract Temperature-pressure experiments have been carried out on gill epithelium of Modiolus modiolus and Mytilus edulis (Baltic and North Seas), as well as on the skin, pharynx, and trunk muscles of Branchiostoma lanceolatum (Pallas), employing the technique of pressure fixation. Temperatures of 0°, 5° and 15°C have been combined with pressures up to 800 atm. Low temperature (0°C) intensifies disintegration of ultrastructures by pressure in comparison to 5°C. The highest degree of structural disorganization can be observed at 600 atm and 0°C. Increased temperature (15°C) increases pressure resistance, but the structural difference is more quantitative than qualitative. In pressure experiments, temperature probably affects cell organelles at the molecular level.

Notes: Abstract Interactions between period and degree of pressure have been investigated in membrane and filament systems of gill tissue, skin, and muscles of Modiolus modiolus, Mytilus edulis (Baltic and North Seas) and Branchiostoma lanceolatum (Pallas) at the ultrastructural level. The results show the importance of time for the degree of structural disintegration at constant pressure. Destruction already occurs after 2 min of low-pressure treatment at 300 atm. After 10 min continued pressure at the same level, no further structural dis-organization (qualitative or quantitative) occurs, even when the time period is prolonged. For some organelles (i.e., cilia and microvilli), better structural preservation is apparent after 30-min pressure compared to 10-min treatment at the same pressure level. This is a so-called “acclimatisation” to pressure.

Notes: Abstract Gill epithelia of Modiolus modiolus and Mytilus edulis (Baltic and North Seas), and the skin, pharynx and muscles of Branchiostoma lanceolatum (Pallas) have been investigated at the ultrastructural level, employing hydrostatic pressure, to explore the possibility of structural regeneration following decompression. Restoration of all cell structures seems possible to a certain extent, depending on the degree of disintegration and the time period given after decompression. Structural reorganization after release of pressure begins immediately, but no regenerated organelle is comrable with control species, since structural “scars” remain. Non-reversible destruction to some systems is apparent near the respective LD50-values of the species.

Notes: Abstract The release of photoassimilated carbon as dissolved organic matter was studied in situ in oligotrophic and eutrophic marine waters and in axenic laboratory cultures. Percentage extracellular release (PER), integrated for the trophogenic zone, ranged from 6 to 12% in eutrophic waters and from 17 to 27% in oligotrophic seas. Most of the algal cultures released low amounts of dissolved organic matter (∼5%) during exponential growth. The highest levels of PER were observed in surface and deep samples, possibly as a result of elevated photorespiration and senescent cells. The generally lower values for extracellular release reported in this work as compared to other studies may be partly due to improved experimental techniques which minimized previously encountered artifacts.

Notes: Abstract This study is based on zooplankton samples collected in the upper 50 m by the F.R.V. “Manihine” in the Gulf of Aden during October–November, 1966 and February–March, 1967. Generally, the displacement volume of zooplankton varied between 20 and 67 ml/m2. Some higher values, up to 100 ml/m2, were also observed. The number of larval fish in positive hauls ranged from 2 to 282 larvae/m2. An inverse relationship between the number of larval fish and the accompanying volume of zooplankton was noted. This relationship is discussed. It is hypothesized that larval mortality due to predation in the Gulf of Aden during the northeast monsoon (November, February and March) was very high.

Notes: Abstract Two allopatric populations of Cardium edule and two of C. glaucum were sampled over a period of 16 months and their gonad maturity cycles compared by histological methods. The onset of both spermatogenesis and oogenesis in C. edule took place between September and October; in C. glaucum it was slightly later, between October and November. Development of the gonads continued slowly throughout the winter, C. glaucum developing marginally faster than C. edule. Maturation accelerated in April and May, with the gonads of both species becoming fully ripe in late May and early June. Spawning of the two species approximately coincided at all the localities investigated. Spawning in C. edule was better coordinated than in C. glaucum. Transplanting cockles of one species to the typical habitat of the other did not appreciably alter the spawning period. The separation of spawning periods in sympatric associations of the two cockles is discussed.