ALBERT

Notizen: Summary The early development of taste sensilla has been studied with special emphasis on cilia, dendrite, and pore formation. In the 39-h stage (the first stage investigated) differentiation of sensilla is already under way. The mechanisms of differentiation of dendrites (39–48 h) deviate from the mechanisms described for differentiation of “true” cilia. In taste hairs the centrioles meet in the tip of the narrowed apical region of the sensory neuron. Together they sink deeper into this region and line up coaxially, thus forming the basal body complex. Thereafter, lateral contacts between this complex and the plasma membrane of the neuron are established. Formation of open connections between the trichogen lumen of the hair and the environment, or the dendrite lumen, was not observed. Electrophysiological data indicate that the sensilla become functional from 3 days before emergence onwards.

Notizen: Summary The fine structure of a paired lamellate body in the anterior region of the lycophora larva of Gyrocotyle urna is described. Each structure is built up by one specialized cell. Lamellae derive from membranes of about 15 cilia that protrude into an intracellular cavity. The lamellae divide into several flattened branches and are rolled up forming a whorl. The lamellate body is presumed to have photoreceptory function. Comparative deliberations are made for similar structures within several platyhelminths.

Notizen: Summary The specialized adhesive exumbrellar tentacles of the limnomedusa Vallentinia gabriella were examined by light microscopy and scanning and transmission electron microscopy. The adhesive region first differentiates some distance from the tentacle tip. As differentiation proceeds the distal part is reduced and the adhesive region comes to lie at the tentacle tip. The adhesive epithelium consists of flagellated and non-flagellated glandular cells, a few nematocytes, and a nerve plexus. The glandular cells are characterized by electron-dense granules and bundles of microtubules. The microtubules, being anchored to the mesoglea, are oriented parallel to the longitudinal axis of the cell and extend up to the cell apex. It can be assumed that the microtubules are involved in the transport of secretory granules to the cell apex. Bundles of neurites run adjacent to the mesoglea between the basal processes of the glandular cells. The neurites form interneural synapses and synapses with glandular cells. It is suggested that detachment of the specialized adhesive tentacles is under nervous control.

Notizen: Summary The topography of the funnel-canal organs of Carcinus maenas (Decapoda, Crustacea) and their stimulus-receiving cuticular and sensory apparatus were studied in the light and electron microscopes. About 4000 funnel-canal organs are situated within the exoskeleton of Carcinus. Almost all of them are on the distal segments of the walking legs, in particular on the epicuticular cap at the tip of the dactyl. They were not found to be arranged in groups or sensilla fields, and no sex-specific differences were observed. Characteristic features of the funnel-canal organs are as follows: (a) There is a terminal pore (0.5×0.8 μm diameter) in the cuticle, at the tip of a small projection. It is closed by a plug of electron-dense material. (b) The terminal sections of the dendrites are enclosed in a dendritic sheath up to ca. 10 μm below the pore. (c) The dendrites, 3–24 in number, end below the plug; none of the dendrites exhibits a tubular body; two of the dendrites are distinguished from the others by the greater number of microtubules in their outer segments. The structural characteristics, in particular the “gustatory pore” and the number of dendrites, are typical of bimodal receptors in arthropods. In such receptors, as in the contact chemoreceptors of insects and arachnids, mechano-and chemosensitive sensory cells are combined. This interpretation of the function of the funnel-canal organs is supported by electrophysiological data of other authors. The morphological parameters we find for the funnelcanal organs, in comparison with those of insect campaniform sensilla, provide clear evidence against the reclassification of the funnel-canal organs as “crustacean campaniform organs” proposed by Shelton and Laverack (1968).

Notizen: Summary Post-embryonic development of parthenogenic eggs of Lepidodermella squammata was studied by light and electron microscopy in animals of known age and reproductive history. Each bilateral gonad initially contains eight cells. No mitotic proliferation occurs during parthenogenic egg development. Germ cells are tightly clustered, have smooth plasma membranes with no interconnections, and are uninucleate. There is no surrounding ovary or oviduct. At hatching, two cells in each gonad are identifiable as parthenogenic eggs. The enlarged nucleolus of the most mature egg has already attained the morphology that persists throughout vitellogenesis, with intertwined granular and fibrillar threads. Less mature eggs have earlier stages of nucleolar development, and lack indications of meiotic events. Parthenogenic eggs enter vitellogenesis singly, with formation of RER and active Golgi complexes, and the accumulation of lipid, yolk, and various granules. The shell is formed in situ, whereas the spines elongate after egg deposition. Most animals produce four parthenogenic eggs, which undergo immediate development (tachyblastic eggs). Resting (opsiblastic) eggs are rare in isolation culture. Both types of eggs are produced only prior to the formation of sperm and primary oocytes. The absence of synaptonemal complexes, which would indicate synapsis of homologous chromosomes in prophase of meiosis I, implies that parthenogenesis is by apomixis in L. squammata.

Notizen: Summary The anatomy of the cecum of the West Indian manatee (Trichechus manatus) is described at the macroscopic and microscopic levels. The cecum possesses a voluminous corpus ceci with two lateral outpocketings; two diverticulae (cecal horns) extend from the corpus at the vicinity of the ileocecal junction. An ampulla ceci is found distal to the corpus ceci, the two compartments communicating via a wide-opened orifice. The most striking microscopic finding is the mucosal covering of a keratinized stratified squamous epithelium overlying the crypts of Lieberkühn. An attempt is made to interpret the morphological observations in terms of the functional digestive process in the manatee, giving alternative suggestions concerning the significance of the cecum and colon in the nutritional status of the manatee.

Notizen: Summary The gemmule shells of fresh-water sponges have a species-specific surface structure, described here for three spongillid species by reference to scanning electron micrographs. The internal structure of the shell is revealed in scanning electron micrographs of sectioned shells released from the embedding medium. Pictures obtained by this method (Weissenfels 1982a) provide information about the architecture of the gemmule shells and the development of the so-called compartmented layer in the gemmule shells of Spongilla fragilis.

Notizen: Summary Histology, physiological regeneration, and degradation of the taenioglossan prosobranch radula and its concomitant epithelia were studied by light and electron microscopy (TEM, SEM), electron microprobe analysis, and autoradiography. Taenioglossa have seven multicellular odontoblastic cushions which produce the tooth matrix by apocrine secretion; many long microvilli are also incorporated. In contrast to pulmonates, the odontoblasts of prosobranchs are capable of division, and their mitoses contribute to the expansion of the cushions, but presumably also to the displacement of degenerating odontoblasts. The seven cushions are isolated from each other by separation cells. The radular membrane is produced from microvilli of membranoblasts and a substance secreted at the base of microvilli. Strands of the supraradular epithelium subsequently move in between the teeth and finally enclose them completely. They effect the hardening and mineralization of the teeth. The strands move together with the radula towards the anterior and are extruded at the opening of the radular sheath; their degeneration, however, has already started in the middle section of the sheath. Epithelial cells are produced by two completely separated mitotic centres which lie dorsolaterally at the end of the sheath. In the subradular epithelium, mitotic activity is scattered over the posterior half of the sheath but is not found in the region where the supramedian radula tensor muscle is inserted. The epithelial cells move forward, but at a much lower rate than the radula. At the opening of the sheath the subradular membrane is generated, while cells of the subradular epithelium lying between the lamellae of the subradular membrane are extruded. The subradular membrane is limited to the functional part of the radula. It is situated on the distal radular epithelium, which is obviously not a continuation of the subradular epithelium. In test animals treated with tritiated thymidine, there is a very strong stationary centre of labeled cells at the beginning of the epithelium, but so far no mitoses have been found in this centre and the labeled cells do not move on continually. In the middle of the distal epithelium mitoses do occur, and the labeled cells permit the assumption that these cells do not migrate at all to the anterior end. At least in Prosobranchia, the distal radular epithelium does not transport the radula to its degradation zone. The transport mechanism for the radula is still unknown.

Notizen: Summary Besides the two axial fibers and the mass of cribellum fibrils, a third component is present in the capture threads of uloborids. This is a substructure originating from the paracribellum. It probably helps to fasten the axial fibers in their position. The axial fibers are secreted from the two glandulae pseudoflagelliformes whose spigots are situated on the posterior spinnerets. It is hypothesized that the cribellum fibrils become jammed and thus fixed between the axial fibers by periodical abduction and adduction of these spinnerets.

Notizen: Summary Processes occurring during moulting in Tetranychus urticae (Acari, Tetranychidae) are described by means of electron microscopy. Moulting is characterized by a pre-ecdysial phase which is initiated by the detachment of cuticle and epidermis. Epicuticular material is deposited as plaques but fuses to form a continuous layer. The epidermis folds up and ridges become determined. Procuticular material is synthesized inside the epidermis and packed into granules which accumulate below the epicuticular portions already deposited. Prior to ecdysis, portions of the old cuticle are dissolved. Ecdysis is achieved by moulting glands which effect bursting of the old cuticle. During the post-ecdysial phase, the endocuticle is synthesized during which a lamellation becomes obvious. Processes occuring during moulting are compared to published information on the tick cuticle.

Notizen: Summary In addition to a male copulatory organ containing a stylet, Polystyliphora filum has numerous uniform prostatoid organs which are arranged in series caudally to the copulatory organ. Each of these prostatoid organs consists of a stylet, extending into an atrium, and caudal to this a bulb. The stylet is funnel-shaped with a curved distal part and a flattened projection in the middle; funnel and projection are differentiated together in a single cell. In an early phase of differentiation, a framework of microtubules is built in the basal part, and this becomes enveloped by electron-dense material. In a later phase, the space between the formed hard structure and the outer membrane of the style building cell is partially filled up with electrondense material. The distal part of the stylet if formed by electron-dense material taken up to the outer membrane. The whole hard structure is differentiated simultaneously and intracellularly. At the same time the whole muscular system of the prostatoid organ is formed. The completed prostatoid organs do not contain sperm, but much coarsegrained medium electron-dense secretion.

Notizen: Summary Mature sperm of the three species, Onithochiton quercinus, Chiton pelliserpentis and Plaxiphora paeteliana are eupyrene and basically of the “primitive” type. The sperm are small, with a distinct head, midpiece with a few spherical to oval mitochondria and a long tail with a (2×9)+2 axoneme. They are unusual among primitive sperm in being bilaterally symmetrical, with a long anterior filament containing an extension of the nucleus and lacking an acrosome. Spermatogenesis occurs synchronously throughout the testis in inwardly folded tissue plates. Spermatogonia arise adjacent to the central blood sinus in each tissue plate. Cells in successive stages of spermatogenesis are displaced towards the luminal surface. The cytoplasm of all stages contains ribosomes, rough endoplasmic reticulum, lysosomes and mitochondria. A Golgi complex is present in secondary spermatocytes and spermatids but does not form an acrosome. During spermiogenesis Golgi complexes are confined to the posterior region of developing sperm and are eventually shed in the residual cytoplasm behind the midpiece. Preacrosomal vesicles are not formed. The long anterior filament of the sperm and lack of an acrosome are features associated with the fertilization of eggs surrounded by a chorion which may have pores or a micropyle. The exact method of fertilization in chitons remains to be elucidated.

Notizen: Summary Marthasterias glacialis bears two kinds of pedicellariae. The straight pedicellariae are single and occur everywhere on the asteroid body surface except in the ambulacral groove. The crossed pedicellariae are clustered on mobile structures (the rosettes) build around marginal and abactinal spines. Basically, each pedicellaria has a head and a stalk. A skeleton occurs only in the pedicellarial head. It consists of two valves and a basal piece. Muscular bundles are anchored on these skeletal ossicles. The straight pedicellariae have two pairs of adductor muscles (the inner and the outer adductors) and one pair of abductor muscles, these latter being weakly developed. Longitudinal muscle fibers occur all along the stalk of straight pedicellariae. The crossed pedicellariae have two pairs of adductor muscles (the distal and the proximal adductors) and two pairs of abductor muscles (the distal and the proximal abductors). The proximal adductors of crossed pedicellariae are homologous to the stalk muscles of straight pedicellariae. The pedicellariae are able to react to direct and indirect tactile stimuli. There is a great deal of individual variation among pedicellarial responses. Moreover, the reactions occur at random and lack coordination. The seemingly aberrant behavior of the pedicellariae is interpreted as a preventive activity that protects the asteroid body surface against unwanted materials and organisms.

Notizen: Summary The cephalic sensory organ in the veliger larva of Rostanga pulchra is situated dorsally between the rhinophores, emerging as a tuft of cilia. This organ is made up of three types of sensory cells, and based on their morphology have been termed ampullary, parampullary and ciliary tuft cells. The cell bodies of the organ originate in the cerebral commissure, and their dendrites pass to the epidermis as three tracts. Dendrites terminate in the epidermis to form a sectorial field. Axons of these cells run into the mass of neurites in the cerebral commissure but no synapses were observed in this area. Morphological evidence suggests that the cephalic sensory organ may function in chemoreception and mechanoreception related to substrate selection at settlement, feeding, or other behaviors.

Notizen: Summary Olfactory trichoid hairs on the antennae of male Antheraea silkmoths were reconstructed with respect to the following parameters: number, shape, course, and dimensions of outer dendritic segments as well as the numbers of their microtubules; inner and outer dimensions of the cuticular hair shafts; and number and distribution of pores and pore tubules in the hair walls. The smallest distances between dendritic membranes and inner hair surfaces were determined with respect to the possibility of pore tubule contacts. It was shown that most hairs contain one thick and one, or frequently two, thin dendrites. The number of microtubules in the dendrites is correlated with dendrite diameter, which decreases towards the hair tip. The dendrites form numerous swellings and constrictions: this “beading” occurs especially along the thin dendrites. The dendrites do not run straight, but rather follow a sinuous course in the hairs. The density of wall pores is lowest in the basal region of the hairs. Only in relatively few places do the dendritic membranes get near enough the hair walls to come into the probable range of the pore tubules. In the sensilla trichodea of A. polyphemus, the hairs as well as the dendrites have markedly smaller diameters than in A. pernyi.

Notizen: Summary Differentiation of spermatids to mature spermatozoa in the bryozoan Tubulipora liliacea was studied by transmission electron microscopy. The spermatozoon of Tubulipora is of a filiform, modified type, and has evolved from the primitive type as an adaptation to a specialized biology of fertilization. The head of the spermatozoon consists of a small, conical acrosome capping an elongated, cylindrical, anteriorly tapering nucleus. A basal invagination in the nucleus contains the proximal portion of the axoneme and a dense attachment matrix. The flagellar axoneme has the typical 9+2 structure. Four elongated rodshaped mitochondria with typical cristae surround the axoneme in the cylindrical middle piece. Granular electron-dense material is accumulated in the form of four columns alternating with four long cylindrical mitochondria. The mitochondrial middle piece is separated externally from the tail region by an involution of the plasma membrane. The tail region contains a cytoplasmic sheath with accessory fibers surrounding the axoneme. Nine outer, coarse fibers extend posteriorly paralleling the nine doublets of the axoneme. The coarse fibers develop from electron-dense plate-like structures associated with the doublets of the axoneme. A characteristic feature in spermiogenesis is that spermatozoa develop in tetrads. There seem to be significant differences in spermatozoan ultrastructure between the three bryozoan classes Stenolaemata, Gymnolaemata, and Phylactolaemata. The differences indicate different lines of evolution of fertilization biology in these groups.

Notizen: Summary The morphology of the retinal pigment epithelium (RPE) and adjacent choroid has been investigated by electron microscopy in the domestic pig. The RPE consists of a single layer of cells which are columnar posteriorly but become cuboidal and even squamous moving peripherally in the fundus. The cells of the RPE layer regardless of location display basal (scleral) infoldings and apical (vitreal) processes and are joined laterally by junctional complexes. Throughout the retina the epithelial cells are rich in smooth endoplasmic reticulum and mitochondria but less so in rough endoplasmic reticulum and polysomes. The epithelial nucleus is vesicular and basally located. In the superior fundus an area of the RPE is very lightly pigmented and richer in lysosomes than is this layer in the inferior and peripheral fundus. The choroid overlying this area is also lightly pigmented and contains much collagen in a lamellar arrangement. This region may represent a vestigial tapetum fibrosum. Bruch's membrane is slightly thicker posteriorly but is everywhere seen to have a pentalaminate substructure. The choriocapillaris is a single layer of large capillaries which show numerous fenestrations facing the RPE. In the superior fundus the choriocapillaris is also highly fenestrated facing the choroid.

Notizen: Summary The pacemakers responsible for initiation of swimming contractions in cubomedusae are located in the four rhopalia. Interneuronal synapses occur between the rhopalial ganglia and the retina cells of lens and cup eyes on one side and the cells of the marginal nerve ring on the other side. Neurites pass from the nerve ring to the neurons of the subumbrellar nerve net synapsing onto muscle cells. The pacemaker system (rhopalial ganglion) is composed of neurons (ganglion cells) containing Nissl's granules. Numerous neurons (interneurons and motoneurons) and nerve fibers make up the nerve ring, most of them oriented parallel to its circular path. While all interneural synaptic contacts are symmetrical, the neuromuscular synapses and contacts between retina cells are asymmetrical (=polarized).

Notizen: Summary A conus-like structure, the hyaloid conus, located on the optic nerve head of the mesopelagic deep-sea teleost Radiicephalus elongatus is described. The hyaloid conus consists of a tapering sheath of unpigmented, vascularized connective tissue enveloping the proximal part of the hyaloid artery which proceeds from the optic nerve head through the vitreous body to the ventrally located falciform process and lens muscles. The hyaloid artery passes through the hyaloid conus without giving off any branches. The conus vessels encircling the hyaloid artery receive arterial blood from the choroid via small arteries and are drained to the choroid by a single vein. The hyaloid conus is compared with the lacertilian conus papillaris. The function of the hyaloid conus is unknown. Because of its small dimensions relative to those of the eyeball and its few capillaries, it is unlikely that the hyaloid conus is a supplemental nutritive device for the retina.

Notizen: Summary The structure of the setae on the proximal antennal segments of the beetle Loricera pilicornis is described using electron microscopical methods. These setae are part of a prey-capturing apparatus and are inserted within flexible sockets. They have no central lumen. Four or five sensory cells are connected to each seta. One cell is characterized as a mechanoreceptor due to the presence of a tubular body and the location of its dendritic outer segment. The other sensory cells are of two types. One type shows the usual features of sensillar receptors except that the dendritic outer segments end beneath the seta within the cuticular sheath. In the other type all parts of the cell, including the perikaryon, appear undersized, and no axon was found. In a single case a sixth cell was found which lacks any process, although, due to its location, it belongs to the sensory cell group. The enveloping cells also deviate from the usual pattern. Trichogen and tormogen cells have no membrane folds nor microvilli. From the membrane of the thecogen cell, where it borders on the inner receptor lymph cavity, invaginations have developed which form voluminous membrane whorls. Portasomes are found on these membranes. On the basis of the structural features we hypothesize that the setae represent sensilla undergoing stepwise reduction, losing primordial gustatory units whilst the prey-capturing mechanism is optimized.

Notizen: Summary The morphology of the rete ophthalmicum, which functions as a brain cooling system, was studied in the desert-origin Bedouin fowl in comparison with two commercial breeds: the White Leghorn and the White Plymouth Rock. Cross-sections of the rete ophthalmicum revealed a significantly higher degree of arteriovenous contact in the Bedouin fowl than in the commercial breeds (P〈0.01). Based on the allometric relationship between the heat exchange area in the rete and body weight, the Bedouin fowl has a significantly higher heat exchange area than non-Bedouin fowls of similar body weights (P〈0.02). These findings suggest that the higher heat exchange area and the high degree of arteriovenous contact in the rete ophthalmicum of the Bedouin fowl is an adaptation to desert conditions, and contributes functionally to the apparently superior heat resistance in this desert breed.

Notizen: Summary In flies, for example the blowfly Calliphora erythrocephala, the thorax has fused to form a chitinous capsule. In it we find three functional types of flight muscles, the indirect flight muscles, the direct, and the tension muscles. The indirect or wing beat muscles transfer their power to the capsule which is capable of oscillating. They are suspended nearly “horizontally” and “vertically”. The direct muscles used for steering insert laterally on the capsule and go to the wing joint. The third functional type of flight muscle serves to put the lateral walls of the thorax under tension. The site and morphology of the flight muscles are described in detail, making use of 3-dimensional drawings. The flight muscles of Calliphora erythrocephala (Heide 1968) and their functions are compared with those of other dipterans described by different authors.

Notizen: Summary The structure of the ocelli of the interstitial gastropod Fartulum orcutti was studied using light and electron microscopy. Each eye is composed of pigmented, rhabdomeric, and ciliated cells. The pigmented cells contain many electron-dense granules and form a cup that shades the sensory cells from all light except that entering from a dorsal-anterior direction. The rhabdomeric cells are similar to the photosensory cells described for other gastropods. They contain photic vesicles and are characterized by an array of microvilli that project into the interior of the eyecup. In the ciliated cells, the ciliary membranes are greatly expanded and form whorls that lie at the front of the eye, opposite the pigment cup. Axons from the bases of rhabdomeric cells have been traced into the optic ganglion, whereas nerve connections from the ciliated cells have not been observed. We suggest that both the rhabdomeric and ciliated cells are photosensory based on their morphological similarities to eyes in other invertebrates. The significance of ocelli with two types of sensory cells is discussed with regard to 1) phylogenetic schemes based on photoreceptor morphology, and 2) the function of such eyes in the interstitial habitat. In addition, the structure of the eye in Fartulum is compared with the description at the light microscopical level of the eye of a related interstitial gastropod.

Notizen: Summary The filtering surface of the branchial basket of Ascidia paratropa (Huntsman, 1912) consists of two adjacent and connected sheets. The stigmatal surface is loosely folded. The secondary gill screen, composed of ciliated longitudinal vessels with primary and secondary papillae, is connected to the stigmatal surface on the inside of the branchial basket. Continuous mucus secretion results in a net with elastic and adhesive properties, and a pore size of less than 0.5 μm in its longest dimension. Net production cannot be interrupted by external mechanical stimuli. The net is usually supported by and transported across the secondary screen, forming a filtering surface that parallels the undulations of the stigmatal surface; however, localized muscular activity of the dorsal laminar fold and longitudinal vessels are also involved in mucous net transport. Squirts occur more frequently than in many species. At these times the net is transported as a flat sheet, independent of the secondary screen. Squiring does not interrupt continuous feeding activity.

Notizen: Summary Retinae of the secondary eyes of a primitive salticid spider, Yaginumanis sexdentatus (Yaginuma 1967) are described at the ultrastructural level. The structures of the anterior lateral, posterior lateral and posterior median eyes are identical. Receptor somata lie in the retinal cups. Each receptor bearing twin rhabdomeres is ensheated by (i) much-divided processes of non-pigmented glial cells whose somata lie distally in the retinal cups; and (ii) four processes of pigmented glial cells whose somata lie basally, below the receptive segments. Pigment granules in the latter are concentrated in the basal retina, and are not present at the level of the rhabdoms. The present findings support the placement of Yaginumanis in a newly erected Subfamily Spartaeinae by Wanless (1984), because of the likelihood of homology in the fine structural organisation of the secondary retinae of this genus and of the genus Portia.

Notizen: Summary The mechanical implications of various types of slit arrangements found among the strain-sensitive slit sensilla in the arachnid exoskeleton (Fig. 3) were studied by measuring the deformation of model slits, cut into plastic discs, under static load applied in the plane of the disc and from varying directions (Figs. 1, 2). 1. Close parallel, lyriform arrangements. Compression of slits (adequate stimulus) reaches much higher values than dilatation. It is highest with the load direction at right angle to the slit axes. Also, in the majority of slits the range of load angles resulting in compression is considerably larger than that leading to dilatation. Length distribution and lateral shift of slits in the models have a pronounced effect on slit deformability (Figs. 4-5): (a) In the “oblique bar” arrangement with slits of equal length and regular lateral shift (Fig. 4A) deformation of all slits is very similar at all load directions. In all slits compression results from a range of load angles larger than 120°. (b) In arrangements with a regular increase in slit length and a triangular outline shape deformability differs greatly among the slits at all load angles (Fig. 4B). (c) The slit configuration with a heartshaped outline (Fig. 4C) is peculiar for the large spread of load angles at which the compression of the different slits is highest. — These properties recommend different arrangements for the solution of different strain measuring problems, with for instance, the particular need of a wide angular working range (arrangement a), of a large spectrum of absolute sensitivities (b), or of the analysis of load direction (c). 2. Angle and distance between slits. Due to the mechanical directionality inherent in an elongated slit the divergence of slit axes within a group of slits is likely to indicate the importance of the analysis of strain direction (Fig. 6). The mechanical interaction between closely neighbouring slits decreases with their distance from each other. In a parallel arrangement of equally long slits it disappears if the distance is about 1.5 times the slit length (Fig. 7). 3. Aiming towards a mechanical model which would explain the complex deformation found in a lyriform organ, we consider the outline of the organ as a hole traversed by beams of material. Slit deformation can be calculated from the elastic lines of the beams which separate the slits and information drawn from photoelastic experiments (Figs. 8-11).

Notizen: Summary Scanning EM investigation of posterio-lateral parts of teleostean fish scales showed that the membranes of their surface epithelium are covered by a complicated system of tuberculi and ridges, forming a maze-system over their cells. These ridges, which are 0.4–0.7 μm high and 0.2–0.6 μm wide, constitute swellings of the cell membrane and form a pattern comparative to the ridge-system found on the skin of higher vertebrates. Epithelial prints of this type were investigated in 43 species of fresh water fish (Cichlidae, Characidae) and marine fish (Serranidae, Apogonidae, Sparidae, Scorpaenidae, Pomacentridae, Girellidae, Gobiidae) of America, Africa, and Asia. The ridge-prints were found to be species-specific, if observed over scales of the same body-site for all individuals. Our investigation, especially on species of the California rockfish (Sebastes), showed that within a given taxonomic group the structure of the ridges is in accordance with the taxonomic as well as ecological relationships of the species involved, usually being more developed in active swimmers and reduced or absent in sessile forms. This research demonstrated that the skin surface microstructures can be used for evolutionary-ecological studies.

Notizen: Summary In the Nematoplanidae and the Polystyliphoridae (Proseriata) a special collar receptor type is found, which differs in two points from the basic pattern of these receptors in the other Proseriata and in the Rhabdocoela: (1) The receptors run between epidermal cells to the surface. (2) In the distal region of the receptor cells an electron-dense cuff is developed. The cuff of these receptors, together with some other features of organisation, is considered to be a synapomorphy of the Nematoplanidae and the Polystyliphoridae, which together form the monophyletic taxon Unguiphora Sopott-Ehlers, 1984.

Notizen: Summary The muscle receptor organs of the mandible of Leuctra extend between the anterior tentorial arm and the mandible base. The ventral receptor is composed of two thin muscle fibres (6–7 μm in diameter) and at least ten multiterminal sensory cells, the dendrites of which branch in the interior of the fibres and end near the z-bands. The dorsal receptor organ consists of three muscle fibres of similar diameter and only one multiterminal sensory cell. The dendritic ends lie at the distal end of the muscle, where muscle fibres and epidermal cells make contact. Both receptor organs essentially show the same ultrastructural characteristics as in Coleoptera. However, the dorsal receptor organ in particular possesses organelles in its dendritic ends, which look like the tubular bodies in ciliary mechanoreceptors.

Notizen: Summary A comparative ultrastructural study of the copulatory organ was carried out in four genera of Turbellaria-Monocelididae. In all four genera the male copulatory organ is of the conjuncta-duplex type and has a cirrus armed with spines. Fine-structural analysis of the cirrus spines reveals that these structures are specializations within the basement lamina of the cirrus. In this part of the male canal the basement lamina has a trilamellar structure. The spines are formed by a local thickening of the middle electron-dense layer and show a structural similarity in all the Monocelididae investigated. The systematic value of this character within the family Monocelididae is discussed.

Notizen: Summary The anatomical and histological details of the respiratory organs and the vascular system of Phyllidia pulitzeri Pruvot-Fol, 1962, are described. The vascular system, especially of the ventral “gill” leaflets, is reconstructed and compared with that of typical Doridacea (Archidoris and Corambe). Within the Phyllidiidae the sinus lateralis maintains its function of returning the blood from the notum to the atrium. This blood is oxygenated by cutaneous respiration. The sinus lateralis also returns the blood from the ventral leaflets. The caudo-medial entrances of the afferent and efferent branchial vessels into the atrium, so typical of all gill-bearing Doridacea, are missing in the Phyllidiidae. The position of the respiratory organs, the mode of multiplication of the “gill” leaflets, the lack of the raphe and of an independent branchial vascular system, and the enlargement of the peripheral vascular system into ventral leaflets show that the “gills” of Phyllidia pulitzeri are secondary specializations of the epithelium of the ventral notum. The heart and the sinus laterales lying bilaterally symmetrical on the viscera, the vascular system, and the respiratory organs seem to be apomorphic features that evolved only once within the Doridacea.

Notizen: Summary The gut of a crinoid echinoderm is described for the first time by transmission electron microscopy. The gut comprises a short esophagus, a relatively long intestine and a short rectum. From the luminal side to the coelomic side, the layers of the gut wall are an inner epithelium, an epineural plexus (much reduced or absent in the intestine and rectum), haemal fluid, smooth muscles mixed with a hyponeural plexus, and a visceral peritoneum. The inner epithelium of the esophagus consists of numerous flagellated enterocytes and some mucous cells containing abundant mucous granules. The luminal surface of the esophagus, but not that of the other gut regions, is covered by a conspicuous cuticle. The inner epithelium of the intestine consists of some exocrine cells, presumably exporting digestive enzymes to the gut lumen, and numerous vesicular enterocytes that are flagellated and contain a few apical mucous granules. The inner epithelium of the rectum is made up entirely of vesicular enterocytes most of which lack a flagellum. The uptake of macromolecules from the gut lumen was demonstrated by feeding the feather stars food mixed with ferritin. By 4 h after feeding, ferritin was identified in presumed secondary lysosomes within the enterocytes of the esophagus and within the vesicular enterocytes of the intestine and rectum. The functional implications of the new fine structural results are discussed.

Notizen: Summary (1) Scanning electron microscopy and vascular casting were used to study the morphology and vascular anatomy of the fully developed internal gills of Litoria ewingii tadpoles. — (2) The four pairs of gills were located in two branchial baskets on either side of the heart. Each gill consisted of a branchial arch with gill tufts projecting ventrally and gill filters running dorsally. The gills bore a variable number of gill tufts in which a complex three-dimensional array of capillary loops, of varying lengths and diameters, was trailed in the path of the ventilatory current. — (3) The evidence presented in this paper suggests that the gill tufts have greater potential as gas exchangers than either the gill filters or skin. — (4) The study revealed structural and functional evidence for the existence of branchial shunts between afferent and efferent branchial arteries.

Notizen: Summary The fresh water sponge Ephydatia fluviatilis contracts rhythmically. At 15° or 16° C the frequency of contraction varies between 4–6 h; the contraction itself takes about 1 or 2 h. Increasing water temperature from 15° to 19° C causes irregular additional contractions, which cease if the temperature is reduced to the initial level (15° C). The results are based upon a non-invasive technique using infrared reflexion.

Notizen: Summary The structure of three cell types in the sensory vesicle is described: (1) The statocyte, with its intracellular statolith, is attached to the medial wall of the vesicle via delicate shaft cells. (2) Cells along the dorsal, ventral and lateral walls which contact the surface of the statocyte with long, slender cilia. These cells are presumed to be primary sensory cells. (3) Presumed secretory cells, along the rostral and dorsal walls, may have a dual function: (a) secretion of the vesicle fluid, and (b) stabilization of the wall by turgor created in characteristic intercellular cavities. The sensory vesicle in Oikopleura contains undoubtedly typical “statocyst components” adequate for a free-swimming animal, whereas the ascidian system is suggested to be a device that responds to gravitational stimuli and, together with temporary photoreceptors, aids the larva in finding optimal settling conditions.

Notizen: Summary Techniques are described for the continuous rearing of the pycnogonid Pycnogonum litorale in the laboratory. The larvae feed as ectoparasites on a polyp, Clava multicornis (Coelenterata, Hydrozoa). From hatching from the egg up to the stage with the definite body shape six moults occur. The first larval stage is the protonymphon. At the first moult it looses adhesive structures typical for this stage. After the second moult three swollen appendices become obvious at the posterior part of the larval body, indicating a region of predominant growth. At each of the four subsequent moults a new segment with one pair of definitive legs each is established by an anamery in addition to the three pairs of preliminary larval extremities. However, at the fifth moult the three pairs of larval legs and the larval proboscis vanish. A much bigger definitive proboscis is established. At the same time the animal changes its host and subsequently feeds on Metridium senile (Coelenterata, Anthozoa). This moult is the main step in the metamorphosis of the larva to the juvenile stage. It is only completed by the growth of one more pair of definitive legs at the sixth moult. The larval stages are described with special regard to the extremities, the proboscis, and fine structures of the cuticle like bristles, spinning- and other gland associated structures, and dorsal humps using scanning electron microscopy. Bristled claws and prickles are explained to have adhesive functions. Newly hatched larvae have a body length of 0.15 mm and grow up to about 1 mm after the fifth moult (change of the host). Under laboratory conditions at 15° C the larval development from hatching to the fifth moult (time point for losing larval extremities and proboscis) takes 67 days in minimum and 83 days in average..

Notizen: Summary The ultrastructure of gill epidermal cells of Diopatra neapolitana and their relationship with blood spaces are described. The existence of a basal infolding complex, related to the blood spaces, is also reported. A possible involvement of these cells in osmoregulation and ion interchange, apart from their well-known role in respiration, is suggested.

Notizen: Summary During fission the ophiuroid Ophiocomella ophiactoides splits across the disc into two halves each of which regenerates to form a complete individual. This paper describes the gross anatomy of the fission plane and the histology, ultrastructure, and mechanical properties of key structures transected during fission. Rupture of the disc integrument appears not to be facilitated by a pre-determined plane of weakness. Comparison of naturally split and artificially split animals showed that at fission a mechanism operates which restricts breakage to the interradial plane of two jaws. The interradial plane is subtended mainly by collagenous ligaments and by muscles linked to the skeletal components by basal lamina-like tendinous fibres. No fission-related adaptations could be identified in the oesophagus, circumoral nerve ring, or circumoral water vascular canal. On the basis of creep tests on isolated preparations of the disc integrument and jaw-frame and the responses of these preparations to ionic manipulation, it is suggested that their behaviour is dominated by collagenous elements that can undergo actively controlled changes in their mechanical properties. A hypothesis is presented which proposes a role for such a mechanism in the initiation and facilitation of fission.

Notizen: Summary 1. The blood supply to cephalic heat loss areas (nasal and oropharyngeal mucosa, bill, eyelids) was studied in mallards by using plastic corrosion casts. The structure and organization of the blood vessels, as well as the occurrence of arteriovenous anastomoses (AVAs), were examined by scanning electron microscopy of vascular casts and by paraffin sections. 2. Submucosal venous plexuses (cavernous tissue) are present in the nasal cavity, tongue, and lateral margins of the palate. These plexuses receive blood from post-capillary venules, but may also receive a non-nutritive component via numerous AVAs. 3. High densities of AVAs were found in the eyelids and in the tip of the bill. In the tongue and nasal mucosa, the AVAs decreased in number caudally. The reason for regional differences in the density of AVAs is discussed in relation to variation in mechanical and thermal stimulation of the tissues. 4. The connection of the different heat loss areas with the Rete ophthalmicum, which is a countercurrent heat exchanger important for brain cooling, is pointed out. The vascular pattern of the head suggests that sphincteric veins are involved in regulating the venous return from the evaporative surfaces of the nasal cavity and palate. One of these veins had, in addition to the normal circular smooth muscle fibres, a conspicuous component of longitudinally arranged, subendothelial, smooth muscle fibres.

Notizen: Summary The larval integument and juvenile girdle integument of Mopalia muscosa (Mollusca: Polyplacophora) were studied by light microscopy. Within 24 h of settlement, eight distinctive changes occur that characterize metamorphosis: loss of the functional prototroch and apical tuft, secretion of a cuticle over the mantle field followed by the secretion of calcareous shell plates and the extrusion of spicules into the cuticle, a 20% decrease in length, secretion of chitinous hairs and the incorporation of the lateral ciliated bands into the pallial grooves. Similar changes which were often not recognized as metamorphic have been reported for other species. Evidence for metamorphosis being a common developmental feature of chitons is presented.

Notizen: Summary The fine structure of the spiral ciliary receptor of three gnathostomulid species is described. Each receptor bears a single cilium — with 9+2 axoneme, basal body and accessory centriole — rolled up in an internal cavity. Spherical and annular cavities are construed as two different types of spiral ciliary receptor. Relations to presumptive photoreceptors in other lower Bilateria and considerations of possible function of these gnathostomulid receptors are discussed.

Notizen: Summary The morphology and fine structure of the vibratile anterior dorsal fin of the rockling Gaidropsarus mediterraneus are described. 60–80 fin rays project as a fringe from a reduced fin web; their lateral movement maintains the fin in almost constant rapid undulation, at a frequency of 3–4 beats per second. The fin can be laid back and with-drawn into a groove. Erector and depressor muscles, which are histologically distinct, move each ray. The fin support is modified, incorporating elastic cartilage, and enclosed in a capsule of collagenous connective tissue. The epidermis at the frontal and caudal aspect of each ray contains numerous receptor cells, over 100,000 per mm2, which have an apical microvillus and synaptic connections with nerve fibres. The recurrent facial nerve sends a major branch to the dorsal fins, which is joined by dorsal ramuli of spinal nerves. It is calculated that there are three to six million receptor cells on the vibratile fin and in the epidermis of the dorsal groove, in individuals of average size. Taste buds do not occur in the skin of the groove, contrary to a previous report, nor on the vibratile fin rays, although they are present on the prominent most anterior fin ray and elsewhere on the fins and barbels. The undulatory motion of the fin draws sea water towards and through the vibratile rays and backwards as a perceptible current. The fin constitutes a specific sensory organ, a water sampler, peculiar to this rockling and related species.

Notizen: Summary Four envelope cells are responsible for the formation of the basiconical sensilla of Calliphora. They are the thecogen, trichogen, and tormogen cells, and envelope cell 4. In early stages of development the still subepithelial sensory cilia are completely enclosed by the innermost thecogen cell. The first formation movements are initiated by a growth thrust of the hair-forming cell into the exuvial space. The sensory cilia only begin to grow into the hair anlage when the hair-forming cell has almost reached its final length. As soon as growth is completed the trichogen cell, tormogen cell, and envelope cell 4 start to excrete cuticular material. The trichogen cell forms the perforated part of the hair shaft and the stimulus-conducting system consisting of the pore tubules. The tormogen cell is responsible for the excretion of the basal non-perforated hair shaft and sheath cell 4 forms the proximal part of the socket region. The thecogen cell only begin to produce dendritic sheath material when the sensory hair is almost complete. Approximately 7–8 days after pupation the tormogen cell degenerates, having, by this time, produced about two-thirds of the sensilla cuticle. The surrounding envelope cells incorporate cell fragments of the tormogen cell. The trichogen cell continues the secretion where the tormogen cell left off. When the secretion of cuticle is finished the sheath cells begin to withdraw towards the proximal direction and to form microvilli on the apical membrane. The resulting outer receptor lymph space is bordered by envelope cell 4 and the trichogen and thecogen cells. The tormogen cell is absent in the sensilla of the imago.

Notizen: Summary In Cupiennius salei (Ctenidae), as in other spiders, the central nervous system is divided into the supraoesophageal ganglion or brain and the suboesophageal ganglia (Fig. 1). The two masses are interconnected by oesophageal connectives. The brain gives off four pairs of optic and one pair of cheliceral nerves. From the suboesophageal ganglia arise a pair of pedipalpal, four pairs of leg, and several pairs of opisthosomal nerves (Fig. 2). 1. Cell types. In the brain a total of 50900 cells were counted, in the suboesophageal ganglia 49000. They are all monopolar cells, found in the ganglion periphery and may be classified into four types: (a) Small globuli cells (nuclear diameter 6–7 μm) forming a pair of compact masses in the protocerebrum (Fig. 10b); (b) Small and numerous cells (cell diameter 12–20 μm) with processes forming the bulk of the neuropil in the brain and suboesophageal ganglia; (c) Neurosecretory cells (cell diameter ca. 45 μm) in the brain and suboesophageal ganglia; (d) Large motor and interneurons (cell daimeter 40–112 μm), mostly in the suboesophageal ganglia (Figs. 10a and c). 2. Suboesophageal mass. The cell bodies form a sheet of one to several cell layers on the ventral side of each ganglion and are arranged in groups. Three such groups were identified as motor neurons, four as interneurons. At the dorsal, dorso-lateral, and mid-central parts of the ganglion there are no cell somata. The fibre bundles arising from them form identifiable transverse commissural pathways (Fig. 9b). They form the fibrous mass in the central part of the suboesophageal mass. Neuropil is well-formed in association with the sensory terminations of all major nerves (Fig. 9a). As these proceed centrally they break up into five major sensory tracts forming five layers one above the other. There are six pairs of additional major longitudinal tracts arranged at different levels dorsoventrally (Fig. 8). They ascend into the brain through the oesophageal connectives and terminate mostly in the mushroom bodies and partly in the central body. 3. Protocerebrum. Fine processes of the globuli cells form the most important neuropil mass in the fibrous core, called the mushroom bodies. These consist of well developed glomeruli, hafts, and bridge which are interconnected with the optic masses of the lateral eyes and most fibre tracts from the brain and suboesophageal mass (Fig. 7). The median eye nerves form a small optic lamella and optic ganglia, connected to the central body through an optic tract. Each posterior median and posterior lateral eye nerve ends in large optic lamellae (Fig. 13a). These are connected through chiasmata to a large optic mass where fibres from globuli cells form conspicuous glomeruli. There are 10–12 large fibres (diameter 9 μm) of unknown origin on each side, terminating in the optic lambella of the posterior lateral eye. The central body, another neuropil mass (Fig. 13b) in the protocerebrum, is well developed in Cupiennius and located transversely in its postero-dorsal region (Fig. 10d). It consists of two layers and is interconnected with optic masses of the median and lateral eyes through optic tracts. Fibre tracts from the brain and suboesophageal mass join the central body.

Notizen: Summary The bursa of Dugesia tigrina is located between pharynx and penis and is suspended in a network of muscle fibers. Two cell types are present in the bursa: small outer cells which likely represent replacement cells and tall inner cells. During copulation seminal material, consisting of secretion products, fibrillar and tubular material, and small clusters of spermatozoa, is injected through the bursa canal into the bursa. During the 48 h post-copulatory period the seminal material is absorbed by the inner cells. Phagocytosis of the seminal material is facilitated by broad apical cytoplasm and modified distal cell membranes. Phagocytosed spermatozoa are enclosed in vaculoes and morphologic breakdown occurs as early as 4 h after copulation. Fibrillar and tubular material is phagocytosed directly into the apical, organelle-free cytoplasm without vacuole formation. The bursa canal is ciliated and the distal cell ends are studded with ultrarhabdites. These are also present in the epithelial cells of the female antrum. Antrum epithelial cells furthermore display apical organelle-free cell areas. Numerous glands penetrate through the antrum wall.

Notizen: Summary The structure of coniferous wood is characterized by pronounced differences in density between earlywood and latewood. This could result in disadvantages in wood strength especially against bending. A summary of the observations in this paper leads to the following hypothesis: Coniferous trees meet this danger by forming numerous stiffenings especially in broad annual rings with a high percentage of earlywood. Such stiffenings may be produced by more or less slight fluctuations of density or chemistry within annual rings in radial as well as in tangential directions. The question remains open which anatomical or chemical reasons, upon sandblasting, locally cause radial or radially branched ribs and craters in cross sections, waviness in radial sections and “cloudy” structures in tangential sections.

Notizen: Summary The reasons for changes in wood quality and utilization are related to the trends toward harvesting smaller, younger and lower-quality timber, wider use of formerly waste wood, unconventional uses of wood, and improved forest management and new wood manufacturing techniques. 1. An unequal distribution of timber along with increasing costs of forest ownership and management is forcing short-rotation forestry, which results in small-sized timber, low-quality wood, and a high proportion of juvenile wood and knots. This is true for almost all forest regions although it has been most evident in tropical plantations. The economic pressures for short-rotation ages will become increasingly great, especially in those areas where a timber imbalance in age class distribution occurs. 2. Especially in the Tropics, many forestry organizations are planting exotic species on a massive scale and are producing a large volume of “different” wood. The trend toward using exotics is very strong. The trees attain a merchantable size at young ages, with thinning being standard; this produces a large proportion of juvenile wood. Such wood is not desirable for some products, based on current quality criteria, and may be distinctly different from the wood that the same species produces in its indigenous environment. Huge amounts of it are now becoming available, requiring a reassessment of both manufacturing techniques and product type and quality. 3. Better utilization in forest harvesting operations results in the use of mill residues of bark and sawdust and forest residues of bark, limbs, leaves, stumps and roots that formerly were considered to be waste. There is also greater utilization of previously unwanted species, including some which were once considered to be of limited value and often were destroyed during regeneration programs. Of great importance are the technological developments that are enabling a greater utilization of the grossly differing woods found growing together in tropical forests, rather than using only a few species and destroying the rest. 4. Wood quality is very responsive to both silvicultural and genetic manipulation. The improvements possible in wood will partially offset some quality declines caused by young wood and lower quality trees. The quickest and easiest method of changing wood quality is to control age of harvest. 5. New industries are developing which use wood as a source of energy and organic chemicals. In some areas, wood for energy is primarily obtained from large forests being planted solely for energy needs and is secondarily obtained as a salvage product from the forest. From 20 to 50% of the wood harvested in the world is for firewood, which often results in a marked reduction of the quality of the wood used for industrial purposes. Currently some research is focused to grow trees which will yield improved energy and chemicals. 6. New manufacturing techniques, such as oriented strand-board and the endgluing of short, clear wood segments from low-quality logs, are enabling the production of high-quality products from low-quality timber. These manufacturing techniques result in products that differ markedly from those previously available but they are stable and of excellent quality. However, a strong sales program will be needed to assure acceptance of the different products.

Notizen: Summary The wettability of four Asian meranti species (dark red, light red, white, and yellow) in various liquids was studied by a cone-immersion technique. Wettability was expressed in terms of the area under the force-immersion curve and referred to as the wettability index. Wettability was strongly influenced by the pH of the solution, generally increasing with increasing pH. Surfactant type affected wettability, with the cationic type yielding the greatest wettability followed by anionic and nonionic types. Among the liquids used, distilled water gave the lowest, and acetone-isopropyl alcohol solution gave the greatest wettability. Of the meranti species, yellow meranti showed the greatest wettability, followed by white, light red, and dark red meranti. A plot of the relative amount of liquid absorbed into the wood sample versus wettability index yielded two regions, one attributed mainly to liquid trapped in crevices on the wood surface, and another which may be more indicative of wood-liquid interactions. A highly significant linear correlation between wettability index and liquid surface tension was found for those species with low and medium wettability, while that with high wettability showed no correlation. A new empirical approach of determining the critical surface tension of wood is discussed. Limited data for the present method indicated close agreement with result from the literature obtained by the use of the well-known Zisman's contact angle approach.

Notizen: Summary A culm sample of Phyllostachys makinoi was investigated by analysis of its chemical composition, and by electron microscopic observations of the cell wall structure before and after extraction and degradation procedures. Quantitative determination of the components resulted in 2.6% extractives, 25.5% lignin, 45.3% alpha-cellulose, and 24.3% polyoses. The main polyose is an arabinoxylan with a Xyl: Ara ratio of about 17:1. The electron micrographs show a lamellar deposition of lignin and polyoses within the secondary walls. Lignin is obviously soluble by parts in alkaline as well as in acidic reagents. Sodium hydroxide solution removes cell wall substance mainly from the secondary walls, whereas trifluoroacetic acid removes substance from compound middle lamellae.

Notizen: Summary Basic density and extractives content, of the sapwood and outer heartwood respectively, were compared for a fast-and a slow-grown tree in five, 40 year old, coppice clumps of each of six eucalypt species. Rate of growth did not appreciably influence extracted wood density, although outer heartwood extractives levels were significantly (P〈0.05) higher in the larger stems. The juvenile core, as defined by radial variation in basic density, occupied a similar proportion of the tree diameter in the fast-and slow-grown trees, suggesting that sampling was effected in tissues of similar maturity in both tree groups.

Notizen: Summary With the emergence of probabilistic design procedures, the need for precise knowledge of the entire probability distributions of load effects and material resistance has never been greater. In order to evaluate these distributions, simulation techniques have provided a reliable and cost and time effective alternative to large scale destructive testing. With the use of the Johnson's SB probability distribution, a closed-form, analytic procedure has been developed to model the inherent variability in strength, given some nondestructively evaluated parameter. This modeling procedure serves as the basis of a verified simulation process to predict a strength distribution, given a probability distribution of the NDE parameter. The approach presented here, represents a closed-form, analytic solution to a problem which has heretofore been treated in a more subjective fashion. This simulation procedure is complemented by a stratified sampling scheme.

Notizen: Summary Pole figures were described for (101), (101), (002) and (040) crystallographic planes of cellulose crystallites in opposite, normal and compression woods of Pinus densiflora. The orientation functions for these planes were plotted on the equilateral triangular coordinate. The orientation factors were calculated from the functions. It was found that the cellulose crystallites in the S2 layer contributed to the orientation distribution although those in the other layers also contributed to some extent. From the equilateral triangular coordinate plots it was found that the orientation distributions of cellulose crystallites in wood varied in some kind of regular fashion. This was more clearly confirmed by the variations of the orientation factors.

Notizen: Summary The transport of heat and moisture during the convective drying of southern pine was examined experimentally. Moisture distribution within the wood samples was measured using gamma attenuation. The accuracy of these measurements was found to be moisture content dependent with estimated uncertainties ranging from 29.5% at 10% moisture content to 6.8% at 120% moisture content. Local moisture content measurements reveal large inflections at high moisture contents. Peaks in moisture content are closely correlated with low fwood density and vice versa. Above the fiber saturation point the measured drying rate is not a well defined function of the moisture content. This is perhaps due to the biological variability of wood as well as grain orientation, although no definite conclusions could be drawn from the data with regard to the effect of grain orientation. The drying rate does not appear to be highly temperature dependent at high moisture contents. Below the fiber saturation point where diffusion is expected to be the dominant transport mechanism, the drying rate is less affected by biological variability and grain orientation, however, the effects of temperature are evident.

Notizen: Summary The increasing supplies of fast-grown woods grown on short roations contain significantly higher proportions of juvenile wood with properties different from those of mature wood. Improved processes will be required to produce dried wood that is satisfactorily stable with few distortional or dimensional changes. The basic wood features affecting different forms of instability are considered. Variations in the amounts of cellulose, hemicelluloses and lignins in wood, the changes in them and the degradation products formed under different conditions are discussed. Changes in the nature of hemicelluloses appear to play an important role in conveying stability. The different volumes of heartwood in green timber have an effect on moisture levels and other properties. As industry is increasing kiln temperatures for high-temperature drying, the effect of time-temperature-moisture relationships on stability and degradation are discussed. The effect of ammonia and other chemicals on stability is considered.

Notizen: Summary During treatment of wood meal with nitrogen dioxide and oxygen the major proportion of the nitrogen dioxide and the intermediate nitric oxide is consumed within a few minutes. On prolonged treatment the concentrations decrease slowly due to regeneration of nitrogen dioxide by reactions between the modified lignin and nitric acid formed in the process. The conversion to nitric acid increases with an increased addition of nitrogen dioxide, a decreased dry content, and temperature. An appreciable proportion of the nitric acid is consumed on prolonged treatment.

Notizen: Summary The interaction between molecular orbital theory and materials science has yielded fruitful insights into the fundamental properties of many substances. The application of these calculations to the chemical constituents of wood may provide an understanding of macroscopic properties by their examination at the molecular and atomic level. The semi-empirical, self-consistent fields method of modified neglect of diatomic overlap (MNDO) was used to study the dehydrogenation of coniferyl alcohol and the electronic structure of the reactive free radicals which form the lignin polymer.

Notizen: Summary This paper concerns the mechanism of noise generation and methods of noise reduction for idling circular saws. Experiments were conducted to examine the sources of saw noise. Saw resonant vibration is proven to be excited aerodynamically rather than by mechanical imbalance. The source of noise generated from a resonating saw and that generated from a nonresonating saw are shown to be identical. A mathematical model is proposed to formulate the dependence of the noise source upon saw kinematic and geometric parameters. Based upon this model and the associated experiments, several potential techniques for noise reduction through design of saw tooth geometry are recommended and discussed.

Notizen: Summary Since Porter (1964), some authors have applied fracture mechanics concepts to wood by assuming that the material is orthotropic and elastic. In order to verify these assumptions, the objective of this paper is to compare experimental results and finite elements computation.

Notizen: Summary An x-ray diffraction method was used to determine the values of the mean microfibrillar helical angles and to estimate quantitatively the amount of crystalline cellulose in the various cell wall layers of wood fibers. To interprete the intensity variation along the diffraction arcs a new curve fitting method based on Gaussian pairs was developed. As an application results are given for Scots pine (Pinus sylvestris) and Norway spruce (Picea abies).

Notizen: Summary The ability of a novel water-borne alkyd resin to penetrate the first and second order void volumes ofTilia americana L. andPinus strobus L. is documented. Penetration of the gross capillary system of both species is evidenced by the creation of high resolution, negative alkyd resin replicas of cell lumina, pit openings and cell wall surface detail. Infiltration of the transient cell wall capillaries present in saturated wood elements is demonstrated by the achievement of moderate antiswell efficiencies of up to 37 percent in small wafers of basswood and 27 percent in Eastern white pine wafers. The alkyd resin without metallic salt driers was present in the cell wall in a non-bonded, and therefore, leachable form. Cell type, character and frequency were found to influence antiswell efficiency and weight percent gain in both species. A low initial wood moisture content and a high resin solids content are requisite for achievement of greater dimensional stability.

Notizen: Summary Variation in density and moisture content of Eucalyptus grandis wood and bark is described utilizing the trees established for a half-sib progeny test in southern Florida. Differences in density and moisture content among progenies were significant. Variations in wood properties were largely due to the genetic differences. No relationship was found between wood density and wood moisture content. Implications for genetic manipulation of wood quality for this species were discussed.

Notizen: Summary The time required to thoroughly preheat/presteam green 8/4 (51 mm) thick red pine and white birch lumber was determined. Thermocouples imbedded in the centre of samples were used to determine presteaming/preheating times for experimental material. These data were then compared to time determined by analytical methods (using formulae developed by Kollmann). No significant differences were found. During the subsequent drying period data were collected on interior wood temperature, mousture content and gradient. Results of the drying tests indicated: i) interior temperature increases in direct relation to elapsed time, ii) moisture content drops exponentially with elapsed time, and iii) an exponential relationship exists between average moisture content and the core temperature of the lumber. Results indicate that monitoring of the lumber drying process through measurements of interior wood temperature may be feasible.

Notizen: Summary The effect of specific gravity upon modulus of rupture, modulus of elasticity in static bending, and maximum crushing strength in compression parallel to the grain was examined for commercially important timbers of various world-wide origins. Data sets were compiled from world literature according to geographic origin. The logarithmic regression of specific gravity vs. the particular mechanical property was calculated by least squares for each data set in the green and air-dry condition. For all data sets, the calculated regression proved to be significant at a 95% confidence level as determined by correlation analyses. Published relationships (U.S. Forest Products Laboratory 1974) were compared to the calculated regressions for the commercially important timber species of the United States and were found to fall within our 95% limits of confidence for each property and moisture content. Covariance analyses revealed significant differences in specific gravity-mechanical property relationships between hardwood and softwood groups. Covariance analyses between data sets from different geographic locations revealed no conclusive trends. Global equations for specific gravity-mechanical property relationships for all data included in this study were shown by correlation analyses to be valid at 95% level of confidence.

Notizen: Summary An attempt is made in this study to relate the gamma-irradiation induced degradation of wood samples to their lignin content and distribution in the cell wall. Samples of Douglas-fir and yellow-poplar were submitted to increasing doses of gamma-irradiation and subsequently extracted with a dilute NaOH solution or with DMSO, prior to SEM observation. Other samples were observed in TEM. The irradiation-extraction procedure degraded the hardwood more than the softwood. In both species, the middle lamella was more resistant than the secondary wall. The S3 layer in Douglas-fir and the warty layer in yellow-poplar appeared to be more resistant than the other secondary wall layers. Some difference was also observed in radiation stability between tracheids or fibres and ray cells. This procedure is suggested as a method for studying lignin distribution in the wood cell wall.

Notizen: Summary Samples of five chipboards, one waferboard, one plywood, one fibre building board and Scots pine timber were loaded in four point bending at a stress equivalent to 60 per cent of the short term failing stress under five combinations of temperature and relative humidity for a period of six months, or until prior failure. Irrespective of whether creep behaviour was assessed in terms of total deflection, viscous component of deflection, relative creep, creep modulus, or deflection at, or time to failure, significant differences were obtained with variations both in temperature and relative humidity. The effect of temperature, at fixed humidity, was slightly greater between 20°C and 30°C than between 10°C and 20°C, while the effect of humidity was appreciably greater between 65% and 90% rh than between 30% and 65% rh. Fitting of hyperbolic curves to the data permitted the prediction of creep behaviour with a good degree of fit at any combination of temperature and humidity within the experimental range. Differences in response to environmental conditions existed among some of the boards. Thus the ranking order of the materials was slightly different under variable humidity than it was under variable temperature. It was possible to describe these differences in terms of the variation that occurred among the materials in the relative proportion of the elastic, viscoelastic and viscous components of deflection.

Notizen: Summary The effect of propylene oxide, butylene oxide, furan resin, and vinylpyrrolidinone in controlling wood dimensional stability have been examined. Wood in the green or ovendry condition was treated with various chemicals using a vacuum-pressure procedure. Treated specimens were tested for tangential swelling, moisture gain, and changes in sorption hysteresis. Results indicate that propylene oxide and butylene oxide enhanced with the crosslinking agent trimethylol propane trimethacrylate, applied to ovendry wood were the most efficient chemical treatments in controlling hygroscopic dimensional changes. The sorption behavior of treated wood as depicted by the ratios of sorption was “very favorable” in most instances. In the case of treatments with furan resin, ratios of sorption were improved from 25 to 100 percent as compared to those of untreated wood.

Notizen: Summary Ultrasonic measurements were carried out on cubic specimens of six species (pine, spruce, douglas-fir, oak, beech, tulip-tree). An orthotropic model of wave propagation was used to interpret these measurements and compute estimates of the elastic compliances. In order to calculate the off-diagonal stiffness terms, velocities were computed on samples with faces at an angle to the principal directions. The elastic compliance matrix was calculated by inverting the stiffness matrix.

Notizen: Summary In the West African Ilomba wood (Pycnanthus angolensis Exell) discolourations frequently develop after felling, which lead to serious degradation with regard to utilization. Therefore, structure and chemical composition of normal and discoloured wood were investigated in order to characterize the original wood and give a detailed account of the reactions which lead to discolourations. According to the results Ilomba, in normal condition, is all sapwood, which explains its high reactivity. The species does not have the ability to develop heartwood; only false heartwood is formed, initiated by exogenous influences. Discolourations arising in the wood after felling are reddish-brown, due to the deposition of extraneous compounds in the lumina of the ray cells. Soluble sugars disappear and the permeability decreases as a result of tyloses development. From discoloured wood only 60% of extraneous compounds could be extracted as compared to the normal sapwood, thus indicating that polymerisation of extraneous compounds takes place. Discoloured wood appears even more susceptible to decay than the bright sapwood. The pH-value increases from about 5.5 to 7.5 during discolouration, and bacteria present within the reddish-brown zones are involved in that process.

Notizen: Summary Dielectric measurements at 3 GHz were made for three softwoods, European pine, spruce and hemlock. The longitudinal, radial and tangential grain directions of the wood were considered as well as moisture contents ranging from 6% to 35%. The positive effect of the moisture content on the loss factor ε″ illustrates the selectivity of microwave drying techniques, while the observations also show that the longitudinal dielectric properties are substantially higher than the transverse ones. The specific effect of the wood species on the dielectric behaviour has to be ascribed mainly to those intrinsic characteristics of the species which influence the sorptive capacity of the wood.

Notizen: Abstract Temporal patterns in the structure and activity of schools of the Atlantic silverside Menidia menidia were investigated under laboratory conditions using a new computerized video technique for three-dimensional analysis. Fish were collected by seining at Middle Bridge, Pettaquamscutt River, South Kingstown, Rhode Island, USA. Approximately once a week from May to December, 1979, the behavior of a school was videotape-recorded in the laboratory at 30 min intervals from sunrise to sunset under a temperature and photoperiod regime simulating ambient field conditions. Four measurements of structure and activity were computed: (1) swimming speed (SPEED); (2) distance to nearest neighbor (NN); (3) mean direction of travel (DOT); (4) depth in the tank (DEPTH). Results demonstrated a strong seasonal rhythm in the behavior of schools, but were inconclusive in showing periodicities associated with daily, tidal or lunar cycles. NN and DEPTH were significantly different between spring, summer, fall and winter while SPEED changed significantly across 3 seasons (summer and winter were not significantly different). DOT was bimodally distributed, with peaks in spring and fall. Changes in these variables corresponded to shifts in the behavior of silversides from active, synchronized schools in spring and fall to inactive mills in summer and inactive non-schooling groups in winter. Changes in schooling behavior were only partly related to changes in temperature and photoperiod. Patterns of silverside schooling behavior correlated with their reproductive and migratory cycles and may represent an anti-predator strategy.

Notizen: Abstract Hermit crab shell adequacy has been inferred by the use of indices, such as the shell adequacy index (SAI). A linear fit of the data, as proposed by the SAI, is inappropriate. The results of fitting a line to the non-linear data are discussed for two independent data sets. Corrections for the data non-linearity reveal that patterns previously attributed to competition within and between crab species may be analytical artifacts of the adequacy indices.

Notizen: Abstract A mass mortality of Strongylocentrotus droebachiensis, attributed to disease, was monitored in an echinoiddominated barren ground at Eagle Head on the south-western coast of Nova Scotia, Canada, in 1982. Mortality was 70% in a shallow (3 m) nearshore area, resulting in a loss of echinoid biomass of 2 042 g fresh weight m-2, and 6% in deeper (7 m, 10 m) offshore areas. Echinoid density, size and nutritional condition (gonad index) were highest in the nearshore area. Survivorship was higher in juveniles (〈15 mm diameter) than in adults resulting in the formation of a bimodal size distribution in the nearshore area. Mortality began around early October, near the peak of the annual cycle of seawater temperature (∼15°C), and was arrested by early December (seawater temperature ∼7°C) when morbid echinoids appeared to recover. In laboratory experiments, time to morbidity of S. droebachiensis exposed to morbid conspecifics increased exponentially with decreasing temperature (20° to 8°C). There was no survival at 20° and 16°C, 20% survival at 12°C and 100% survival at 8°C after 60 d; suggesting a lower temperature limit (between 12° and 8°C) for possible transmission of a pathogenic agent. Morbid laboratory echinoids from experiments at 16°C, and recovering echinoids collected in the nearshore area in early December, showed 100 and 85% survival respectively at 〈=8°C, and 0 and 15% survival respectively at 16°C, after 30 d. Time to morbidity was not affected significantly by nutritional condition and was similar for juvenile and adult echinoids. Time to morbidity was greater in echinoids exposed to one or three morbid individuals continuously, or seven morbid individuals for 1 h, relative to higher levels of exposure (up to seven morbid individuals continuously). Recent mass mortalities in S. droebachiensis have occurred in years of record high sea surface temperatures. The extent of mortality is correlated with the magnitude and duration of temperatures above a lower limit.

Notizen: Abstract Aspects of feather star behavior and ecology were recorded by time-lapse cinematography approximately 1 frame min-1 on the Great Barrier Reef, Australia over a 1 mo period in 1983. The current regime influenced body postures of most species studied, whether nocturnal or not. Moreover, feather stars of several species crawled on the substratum with their arms; each crawling episode lasted roughly 10 min, and the maximum speed attained was about 1 arm length min-1. Nocturnal feather stars crawled to their nighttime feeding perches around dusk and crawled back to their daytime hiding places around dawn. Surprisingly, some species of feather stars living on the reef surface both day and night also crawled around at dawn and dusk for reasons that are not known. In the time-lapse films, and individual of Comanthus bennetti (sex undetermined) spawned for about 2 min just after dark on 5 July 1983. Another film showed possible predation on a feather star (Himerometra robustipinna) by a saddled coralfish (Chaetodon ephippium).

Notizen: Abstract A directed translocation of 14C-labelled photoassimilates was shown to occur in the thalli of six species of brown seaweeds belonging to the Fucales. The apical growing regions of these algae act as strong sinks in the “source-tosink” relationship of the long-distance transport. Physical interruptions of the thalli showed that the midrib is the main pathway of the assimilates in Fucus vesiculosus and F. serratus. 14C-histoautoradiography has shown that translocation takes place through the filamentous cells of the medulla. The translocation velocity of the labelled assimilates, calculated from time source profiles of the tracer, was estimated to be 2 to 4 cm · h-1. It is suggested that the sieve elements of the Fucales act in a way similar to the conducting sieve elements of the Laminariales.

Notizen: Abstract Solitary radiolarians (Spongodrymus sp.) in laboratory cultures consumed 14C-labeled Amphidinium carteri and Coccolithus huxleyi more than Isochrysis galbana or Thalassiosira fluviatilis. The ratio of A. carteri protein consumed per unit time to the amount of Artemia sp. nauplius protein consumed (P/Z) was 6.7×10-2 indicating that these omnivorous radiolarians tend to consume more zooplankton protein than phytoplankton protein.

Notizen: Abstract Nucella (=Thais) lapillus (L.) develops to the juvenile stage within an egg capsule. This study was undertaken to investigate nutritive and bacteriostatic properties of the intracapsular fluid for this species. Capsules were collected intertidally at Nahant, Massachusetts, USA, in the summers of 1982 and 1983. The average capsule contained only 1.1 μl of intracapsular fluid per embryo. A statistically significant correlation was observed between capsule height and number of developing embryos contained therein, although the number of embryos per capsule was more closely related to capsule volume. Total dry weight of encapsulated, shelled embryos increased exponentially as a function of shell length. However, weight increases may be entirely due to shell calcification; the average dry tissue weight of shelled embryos was significantly below that for pre-shelled individuals, suggesting a net loss of biomass during development. Aliquots of intracapsular fluid failed to inhibit the growth of the 13 bacterial strains tested. Despite the above results, pre-shelled embryos generally survived only several days following their premature removal from egg capsules at 12°C. Shelled veligers were reared outside of the capsules with no apparent ill effects. An explanation for these survivorship results is elusive.

Notizen: Abstract The rare ctenophore Haeckelia rubra (formerly Euchlora rubra) has long been known to have nematocysts rather than colloblasts in its tentacles. Five specimens were collected in the San Juan Archipelago, Washington State, USA in 1980 and 1981, and their feeding behavior was observed in the laboratory. We found that H. rubra readily eats the tentacles of a medusa, Aegina citrea, whose nematocysts (apotrichous isorhizas) are nearly identical in morphology to the nematocysts of the ctenophore. When H. rubra was offered 16 other species of hydromedusae and 1 siphonophore in the laboratory, the ctenophores showed little or no tendency to ingest these potential prey items. In addition to its routinely positive response to A. citrea, the ctenophore could be induced by manipulation and starvation to accept and ingest bits of the bodies of 4 additional species of hydromedusae and 1 siphonophore. These results, combined with the histological and rearing experiments of other investigators, leave little doubt that the nematocysts in H. rubra are not endogenous, but are “kleptocnidae” similar to those nematocysts retained and subsequently used by some species of nudibranchs that feed on Cnidaria. A close phylogenetic link between the Cnidaria and the Ctenophora is most unlikely.

Notizen: Abstract The relationship between food ingested and NH + 4 excretion rate was investigated for female Calanus pacificus collected in August, 1982, from the San Juan Archipelago, Washington State, USA. The copepods were preconditioned to 6 densities of the diatom Thalassiosira weissflogii (0 to 104 cells ml−1) for 30 h before the experiment. The experiment was conducted with nutrients added in excess to maintain equal rates of NH + 4 uptake by the diatoms at all densities. Although ingestion rates of C. pacificus varied from 0 to over 20% of body N d−1 at the different food levels, excretion was a constant 6.6 nM NH + 4 copepod−1 h−1 or about 10% of body N d−1. This ingestion-excretion relationship, which is consistent with previous respiration and fecundity studies, suggests that the ecological dominance of C. pacificus only under conditions of high food abundance may be due to a dramatic increase in its growth efficiency as ingestion increases above the level supporting a constant metabolic rate. The maintenance of a constant level of metabolism during relatively short periods of low food abundance may be advantageous if it allows the copepod to exploit more effectively short-term variability in its food resulting from environmental heterogeneity or vertical migration.