ALBERT

Notes: SYNOPSIS. When two strains cf T. pyriformis that do not require exogenous pyridoxine are crossed, all progeny grow without the vitamin. Offspring from crosses of two pyridoxine requiring clones require pyridoxine with the exception of a few which will grow without pyridoxine. The ratio is approximately 3:1 favoring the pyridoxine requiring category. In matings involving the homozygous dominant pyridoxine requiring clones with the double recessive mutant, that is +/+ X p/p, all of the resulting progeny need pyridoxine. Test crossing these heterozygotes (+/p) with the parental pyridoxine non-requiring clones (p/p) gives offspring approximating a 1:1 ratio. Matings between two heterozygotes derived from breeding experiments also yield progeny in approximately 3 pyridoxine requiring: 1 pyridoxine non-requiring. All data indicate selection for the heterozygote in the population and a possible selection against either homozygote. The great abundance of heterozygotes and rarity of recessive homozygotes in natural habitats corroborates these findings. The genetic evidence supports a single gene hypothesis although the possibility of multiple closely linked genes cannot be ignored. There is also the possibility that a dominant suppressor gene may function in blocking the activity of the pyridoxine mutant genes. Moreover, if this gene exists it may be incompletely dominant since the heterozygote grows slightly on deficient media.

Notes: SYNOPSIS. Trichodina urinicola was found in newts, Triturus cristatus and T. taeniatus, in three localities in Czechoslovakia. The ciliate populations showed important differences on the basis of which they were separated as three new forms of this species: T. urinicola f. typica, T. urinicola f. bohemica, both from Triturus cristatus, and T. urinicola f. taeniatus from Triturus taeniatus. The great variability of trichodinids is evident from the literature as well as from our own observations, so that these new forms are to be regarded as provisional ones until it is possible to decide on the basis of a large number of observations the extent of specificity and variation of individual endozoic species of Trichodina. A detailed description of these forms is given as well as a comparison with the known species of trichodinids inhabiting the urinary tract of amphibians. A brief comment on the present taxonomy of the Urceolaridae in general is outlined.The need for a uniform description of these ciliates is emphasized; in connection with this, the taxonomic value of individual body characters is discussed. Special attention is paid to the adhesive disk of Trichodina, the structure of which is of greatest importance in the taxonomy of this group. On the basis of Dogel's and Fauré-Fremiet's descriptive methods employed in study of trichodinids, a proposal of a uniform description of Trichodina is made which involves all the important features of these protozoa.

Notes: SYNOPSIS. Several substrains of Euglena gracilis var. bacillaris made chlorotic by treatment with pyribenzamine or streptomycin, or by growth at high temperature (35–36°C.), have been examined for their carotenoid content. They differ from the normal green strain both qualitatively and quantitatively. Some strains produce no detectable carotenoids while the carotenoid concentration in the strains producing most is at best only one-fifth that of the normal strain. In all substrains producing carotenoids, the carotene fraction consists of β-carotene accompanied by some members of the phytofluene series. In only two of these substrains, HB-G and PBZ-G3, are xanthophylls produced in significant amounts. In HB-G, the main pigment is echinenone, and in PBZ-G3 it is zeaxanthin. The significance of these findings is briefly discussed.

Notes: SYNOPSIS. Association of gamonts of Pyxinia crystalligera takes place in the midgut of its beetle host, Dermestes vulpinus. At 25°C. the development of gametocysts to the point of liberation of sporocysts is completed between about 15 hours and 27 hours after the gametocysts are deposited with fecal material. Dehiscence is favored by relative humidities of 0% to 90%, but is not favored by a relative humidity of 100%. During the early development of the gametocysts outside the host, the crystals and paraglycogen granules in the cytoplasm of the associated gamonts become concentrated in large masses. The gametes are formed at the periphery of the gamonts. After fusion of the gametes takes place and the sporoblasts begin to develop, the residual cytoplasm containing the inclusions moves outward to form a continuous layer next to the gametocyst envelope, so that the sporoblasts become crowded into a central core. A few hours before dehiscence is initiated a clear area appears on the upper side of the gametocyst. The contents of the gametocyst begin to shrink away from the envelope except in the region of the clear area. Eventually the sporocysts emerge through the clear area and press against the envelope of the gametocyst, causing formation of a conical papilla in the envelope. With continued pressure from the sporocysts, the papilla ruptures at its tip, and the sporocysts emerge in a continuous thread until dehiscence is completed. The thread of sporocysts may attain a length of about 11 mm.

Notes: SYNOPSIS. The steps leading to purine ring closure were examined in Strigomonas oncopelti. The flagellate has an obligate adenine requirement (hypoxanthine and guanine are inert) when grown without p-aminobenzoic acid. The imidazole counterpart of adenine but not the imidazole counterpart of hypoxanthine was active. A pathway for purine biosynthesis compatible with these results is sketched.

Notes: SYNOPSIS. The Nuttallia of the gerbil is transmitted by Rhipicephalus secundus only if the infected meal is taken by the larva, and the subsequent nymphal stage is the only one which is able to infect. There is no transovarial transmission.Infective trophozoites remain in the larval caeca for about 12 hours after gorging. The infective nymph is able to give rise to new infections at various times after it has been allowed to feed, but never later than the third day after disengagement from the host.

Notes: SYNOPSIS. The process of autogamy in unassociated individuals of Paramecium polycaryum was reported by the author in 1954. In May, 1955, conjugation was first seen in this species in cultures collected by me at Annamalainagar, South India, thus removing it from the list of non-conjugating species. This appears to be the first instance in which the process of autogamy was detected prior to observation of conjugation in the same species. Autogamy occurs in singles of the Indian race and appears to be similar, cytologically, to that of American races. The details of the micronuclear behavior in conjugation parallel those of autogamy in singles. In fact, the conjugation process seems to be one of double autogamy (cytogamy), rather than of reciprocal gametic interchange. Paroral cones, often of fair size, are formed but breakdown of the cones to permit micronuclear passage has not been observed. In conjugation there are the usual three pregamic divisions; the first shows four characteristic crescents. The resulting nuclei may all participate in the second division. Fertilization occurs in the paroral cone area. Frequently, separation of the conjugants takes place immediately after the first division of the synkaryon. The old macronucleus undergoes very little change prior to the last postzygotic micronuclear division in the ex-conjugant, when it goes into a skein condition. Four macronuclear and four micronuclear anlagen are formed in the ex-conjugants at the completion of reorganization. On occasion giant individuals of P. polycaryum were observed to have ingested numbers of Tetrahymena pyriformis. The presence of an unidentified rod-like organism in the cytoplasm of the paramecia (non-conjugating) was detected in one collection from Bangalore, India.

Notes: SUMMARY. A study has been made of the cytology of an undescribed species of Spirostomum. The species is much smaller than S. ambiguum. The peristome extends to about half the length of the animal, whereas in S. ambiguum it is about two-thirds the body length. The nuclear apparatus reveals some striking differences. The macronucleus is cylindrical, and not chain-like, in the vegetative animal. The micronuclei are far fewer than in S. ambiguum and number 6–15, but are larger in size. During binary fission, the macronucleus becomes condensed into an oval or polymorphic mass and is drawn out again into a cylinder before it is cut into two lengths. The micro-nuclei divide by mitosis and, whatever their number in the vegetative animal, only 7–8 take part in the division. The others presumably degenerate.

Notes: SUMMARY. The structure and life history of a new species of eugregarine, Gregarina garnhami n.sp., is described from the intestinal caeca and mid-gut of Schistocerca gregaria Forsk. The parasite destroys considerable areas of the caecal epithelium and in cases of heavy infection, the masses of parasites present in the mid-gut result in the formation of localized barriers between the gut wall and the food material in the lumen. The cephalont and sporont stages of gregarines from Locusta migratoria migratorioides R. & F. and Anacrydium aegyptium Linn. are shown to be similar to those from Schistocerca gregaria and are believed to belong to the same species.

Notes: SUMMARY. Oxygen concentrations of 70–80 per cent of an atmosphere destroy all chromosomes of the flagellate Trichonympha provided the oxygen treatment is carried out during the early stages of gametogenesis at which time the chromosomes are in the process of duplicating themselves. This treatment does no damage to the cytoplasm and its organelles. Following the loss of chromosomes, the centrioles function in the production of the achromatic figure, the flagella, and‘parabasal bodies. Then the cytoplasm divides, thus producing two anucleate gametes which make some progress in the cytoplasmic differentiations characteristic of normal male and female gametes of Trichonympha.It is also possible, with somewhat higher concentrations of oxygen, with temperatures slightly above the freezing point and a longer period of treatment, to destroy the chromosomes of resting asexual nuclei in several genera of the flagellates that live in the roach Cryptocercus. So far as one can determine by observing organisms so treated, their cytoplasm and organelles are not injured.

Notes: SYNOPSIS. The effects of some environmental influences on the cycle of Trypanosoma diemyctyli in Triturus v. viridescens are described. Bleeding of the host produced a reduction in the number of trypanosomes but did not affect their growth rate. The temperature at which the host was maintained affected the cycle of the trypanosomes. The length of the post-inoculation latent stage increased from 24 hours at 25°C. to an indefinitely long time at 5°C. The trypanosomes were found to be dimorphic. Adult parasites of the short form had a range of 45–75 μ and those of the long form of 76–116 μ. Growth rate of the trypanosomes was inhibited or greatly retarded at temperatures of 10°C. or lower and was greatest at 25°C. The size attained by the parasites and the number of parasites were greatest at 15°C. At this temperature the infection was pathogenic and the dimorphic parasites were in their long form. At the higher temperatures (20–25°C.) the infection was non-pathogenic with the trypanosomes in their short form.The infection is primarily one of adult newts. Experiments indicated that the larvae were resistant to the trypanosomes at all temperatures while the red efts were not. The latter are usually free from the trypanosomes because they are not exposed to them. Attempts to infect other newts and to locate any cryptic stages by the injection of blood and tissues from infected newts gave negative results.Starvation, sodium salicylate, and treatments used to control fungus infection of the newts had no detectable effects on the trypanosomes.

Notes: SYNOPSIS. A comparative study of five species of Tetrahymena, including thirteen strains, was made to ascertain their ability to act as facultative parasites. A variety of experimental hosts, including both vertebrates and invertebrates, were inoculated with axenic cultures of protozoa. Infections were numerous in both larval and adult insects. Tissues of living vertebrates were invaded by one species of Tetrahymena through artificially produced wounds.

Notes: SYNOPSIS. Unabsorbed, complement-inactivated antisera produced in rabbits were used in an immobilization system to study the serology of 31 strains of Tetrahymena pyriformis grown in axenic cultures at 26°C. Fourteen serological “groups” were found: 1. “H”: H, E, S, GC, L3, W, T, GHH, G1-R and sublines W-P and T-P; 2. “PR”: PR; 3. “GL”: GL; 4. “LR”: LR; 5. “L1”: L1 and L2; 6. “GP”: GP and Ch-S; 7. “WH”: WH6, WH14 and WH52; 8. “N”: N and HS; 9. “Y”: Y and TC; 10. “AA”: AA1, AA2 and AA4; 11. “F”: F and BF; 12. “Gf-J”: Gf-J; 13. “EZ”: EZ; 14. “Lava”: Lava. Not all of these “groups” were completely distinct; weak or variable cross-reactions occurring for particular cultures and antisera during the course of several years of observation suggested a relationship in terms of serotype potentialities, for strains in groups 1 and 2, and in groups 2, 3, 4, 5, and 6. Non-reciprocal cross-reactions are tentatively explained in terms of population fluctuations of serotype within particular cultures; several other suggested explanations remain possible. On the whole, however, the strains remained remarkably stable in dominant serotype.Observations on Tetrahymena in paralyzing antisera, with respect to the extrusion of a gelatinous exudate, in general confirmed previous observations by others. “Chain” formation was noted upon recovery, under conditions suggesting that the chains do not always derive entirely from incomplete cytokinesis of dividing organisms but that at least sometimes an aggregation of separate individuals is also involved. Synchronized division was observed for recovering organisms. A gelatinous material was obtained by centrifugation of a large number of individuals; this material provided a degree of protection to the organisms against antiserum effects while other colloidal materials did not, but the protective effects proved nonspecific in the sense that they were not confined to particular strain-antiserum combinations.

Notes: SYNOPSIS. A rapid quantitative method for measuring trypanostatic activity by means of the nonpathogenic flagellate Herpetomonas culicidarum is described. Of the known trypanocidal agents tested, pentamidine was the most active; stilbamidine and propamidine somewhat less active. H. culicidarum is more resistant to these agents than are some pathogenic hemoflagellates. Two new antifungal antibiotics, nystatin and heptamycin (a candicidin-like antibiotic), had powerful trypanostatic activity in vitro. The potential trypanostatic activity of antifungal agents is noted.

Notes: SYNOPSIS. Approximately fifty % of Natrix piscator from the vicinity of Bombay showed a haemogregarine in the peripheral blood. Schizogonic stages were found in great abundance in the lung capillaries, and occasionally in other internal organs. No parasites could be demonstrated in trombiculid mites of the genus Schongastia fed on infected snakes. Various developmental stages were found in the leech, Hirudinaria granulosa allowed to feed on infected Natrix piscator. The haemogregarine was originally described from this host in Ceylon on the basis of blood stages only and was named Haemogregarina mirabilis. Although the parasite exhibits several of the characters diagnostic of the schizogonic stages of the genus Hepatozoon, it is advisable for the present to retain it in the genus Haemogregarina.

Notes: SYNOPSIS. A new species of a freshwater reticulate dinoflagellate, Woloszynskia limnetica, is described. The membrane structure and the shape of the membrane plates change during cell development. The rod-shaped mitochondria found among the membrane plates disappear in the adult cells; they constitute a center from which starch grains develop. Mitochondria also occur free in the endoplasm. Different physiological activities appear to be performed by morphologically identical chondriosomes. The stigma changes in different phases of the life cycle. The physicochemical properties of the ectoplasm govern the formation of specific structures of the membrane plates, which in turn determine the taxonomic position.

Notes: SYNOPSIS. Pseudomicrothorax dubius, a rather rare protozoon assigned by Kahl to the trichostome order of ciliates, has been found and positively identified for the first time in America, and its morphology and morphogenesis have been studied in detail with the aid of modern techniques. The Chatton-Lwoff silver impregnation method is considered indispensable in acquiring an understanding of the ciliate's infraciliature: both its anatomy in the mature vegetative animal and its activities during the morphogenetics of binary fission.Stomatogenesis is of a complex type, considered here as “semi-autonomous” in nature, although a single, true stomatogenous meridian also is involved. Details of this explicit morphogenetic phenomenon are offered.The presence of a true zone of three adoral membranelles, never before recognized with any accuracy in this ciliate, a buccal cavity and associated structures, and the mode of stomatogenesis have led the writers to propose transfer of the genus Pseudomicrothorax from the Trichostomatida to the order Hymenostomatida.

Notes: SYNOPSIS. Studies of the body ciliature of Balantidium coli and B. caviae (?) after Breslau's opal-blue and Klein's silver nitrate techniques revealed a preoral-dorsal suture area where some of the ciliary rows fail to reach the peristomial margin. The incomplete kineties ranged up to a dozen in number and were variable in arrangement. In a count of 100 specimens of B. caviae (?) the incomplete kineties were at the right of the suture in 39, at the left in 24 and on both sides of the suture line in 37. At the posterior end not many kineties reach the pole but no sutural pattern was seen in that region. Scattered irregularities in the ciliary rows were sometimes seen.Studies of the oral region tend to confirm the view of Fauré-Fremiet that the peristomial ciliature consists of short rows of cilia which are continuations of the anterior body kineties. Membranelles were not found. Thus, some species of Balantidium, at least, show affinities with the Holotricha in agreement with Nie and Fauré-Fremiet.Fission commonly produces two equal-sized daughters but many cases of unequal division were observed. In both these species conjugants are much smaller than vegetative animals and two preconjugant divisions are indicated, the first of which may be unequal.During the early stages of fission, the anterior ends of the kineties of the posterior daughter change direction, becoming oblique in the fission zone. In this region the kinetosomes multiply; possibly some of the kineties also divide but evidence for this is incomplete. No evidence of reorganization at the anterior end of the anterior daughter was seen.Attempts to infect hamsters with B. coli and B. caviae (?) failed. No parasites were found in two collared peccaries repeatedly examined.

Notes: SYNOPSIS. Purification by migration on solid agar plates was studied with a small soil amoeba, Acanthamoeba sp., and a large fresh-water amoeba, Amoeba proteus. Purification seems accomplished largely by two mechanisms: egestion and attrition of contaminating organisms. Digestion may also play a role but probably is less important. The migration method is applicable to motile forms of the two amoebae which differ greatly in volume and motility. Therefore the method may be of potential value in purifying many species. Modifications which should extend the usefulness of the method are considered.

Notes: SYNOPSIS. The gametes of Trichonympha grandis fuse quite differently from those of all the other species of Trichonympha in Cryptocercus; fusion is partial and temporary instead of complete and permanent as in other species. In this species, as in the others, fusion brings about the disintegration of all the extranuclear organelles of the male gamete, but none of those of the female; these persist to become the organelles of the zygote. Gametic union accomplishes two things: loss of extranuclear organelles of male and fusion of pronuclei. Unlike that of the other species of Trichonympha, the cytoplasm of the male gamete of T. grandis contributes slightly, if at all, to the formation of the zygote.

Notes: SYNOPSIS. A new species of Hepatocystis (H. hippopotami) is described from the blood and liver of a Rhodesian hippopotamus (Hippopotamus amphibius). Its relationship with other members of the genus is briefly discussed.

Notes: SYNOPSIS. The role of eleven different types of achromatic figures in chromosomal movement of Barbulanympha is analyzed. When only one pole is present, no chromosomes are ever connected with it, and hence they do not move. The chromosomes go through their usual life cycle including pairing, but remain in the parent nucleus, which, of course, does not divide. When two poles are present with only one pole near the nucleus, the poles, which are the distal ends of the elongate centrioles, do not cooperate in the formation of a central spindle and the chromosomal behavior is just as if there were only one pole—no movement. The same is true when more than two poles are present with only one near the nucleus.Unless a central spindle is present, movement of chromosomes never occurs. However, when many central spindles are present, sister chromosomes may separate and move to poles which are not directly connected by a central spindle. In other words, sisters may separate without moving along a central spindle.In binucleate cells with one central spindle the chromosomes of one nucleus move to the poles, but those of the other do not. Movement always occurs in the nucleus that has its nuclear membrane depressed by the central spindle. When two or more central spindles are present, the chromosomes of both nuclei may move to the poles.

Notes: SYNOPSIS. Euplotes eurystomus Wrzesniowski was cultured on bacterial media with Tetrahymena pyriformis serving as the food organism. Animals were injured with various types of operations using the Chambers' micromanipulator. These animals were followed during the course of their regeneration using various nuclear stains, silver impregnation techniques and vital staining methods. It was found that two cirral fields arose as a result of injury removing one or more of the locomotor organelles and that the posterior field was soon resorbed, while the anterior one replaced all of the old cirri of the regenerating animal. In addition, in response to this sort of injury, complete nuclear reorganization took place. Animals which were injured in a manner not affecting the locomotor organelles directly, responded by proliferating a fine network in the area of injury. This network seemed to reinforce the injured area and persisted until the next binary fission of the animal. No nuclear reorganization took place in these cases.

Notes: SYNOPSIS. The leech, Erpobdella sp., is a suitable invertebrate host for Trypanosoma ambystomae. The developmental cycle involves a mononucleate, rounded body derived from the bloodstream form; this body then transforms into a large plump crithidia. Subsequent divisions yield medium crithidia, small crithidia, and ultimately, metacyclic trypanosomes.

Notes: SUMMARY. Known chemical compounds have replaced the three supplementary factors previously necessary for the growth of Euplotes patella feeding on Chilomonas paramecium under bacteria-free conditions. The factor found in an extract of liver was identified as thiamine. The factor supplied by extracts of certain bacteria has been tentatively identified as folinic acid. A combination of 8-azaguanine and the riboflavin analog, flavotin, has been substituted for the factor found in yeast extracts. Inorganic salts and sodium acetate have been incorporated in the supplementary medium to promote the growth of the flagellate food organisms. Euplotes has also been cultured on Tetrahymena pyriformis in a medium containing 8-azaguanine and flavotin. The requirement for supplementary growth factors in this carnivorous ciliate has been interpreted as definitely involving intermediates in purine metabolism.

Notes: SUMMARY. An improved assay of vitamin B12 is described. The z strain of Euglena gracilis, which grows more vigorously than the bacillaris strain previously used, is recommended. The pattern of B12 specificity of the two strains appears to be the same. A new medium containing sucrose, aspartic acid, glutamic acid, and glycine at pH 3.6 is well buffered and allows luxuriant growth. Vigorous utilization of sugar appears to depend on readily available nitrogen and a Krebs-cycle component; these requirements are well met by aspartic acid (or asparagine) and glutamic acid. The proposed procedure is especially suitable for the measurement of B12 in blood serum because rise in pH and precipitation of serum proteins during incubation are minimized. Like bacillaris, the z strain allows the distinction between “combined” and “uncombined” B12 in serum. Serum may be an appropriate test material to tell whether such phagotrophs as Peranema can better utilize bound forms of vitamins than can the related osmotrophs. Patterns of B12 requirements and occurrence are discussed as phylogenetic markers.

Notes: SUMMARY. Cells from a clonal culture of Tetrahymena pyriformis W were cultured in the presence of 10-4 M KCN for a prolonged time until they became “adapted” to cyanide. The effect of 10-3 M KCN upon respiration in the “adapted” cells was compared with the effect upon “normal” cells of the same clone grown in the absence of cyanide. The direct method of Warburg was employed.Adapted cells are more resistant against respiratory inhibition than are normal cells. Resistance is due both to a factor or factors retained within the cell and the extracellular factor(s) released into the medium by the adapted cells during their growth. The intracellular factor is acid labile, and apparently may be developed within a short time. The extracellular factor is heat labile and may cause normal cells to be more resistant against respiratory inhibition by KCN.Resistance to respiratory inhibition is lost if adapted cells are cultured in the absence of KCN. It is proposed that changes involved in gain or loss of cyanide resistance are due to physiological adaptation and not to the usual genetic influences.

Notes: SUMMARY. A neopeptone blood broth was a satisfactory medium for cultivation of the frog trypanosome T. ranarum, though it did not support as consistently good growth as the corresponding diphasic medium. The superiority of diphasic over liquid medium could be explained only by the presence of a reserve of nutrients in the agar slant which diffuse into the liquid phase. Inocula from culture tubes 12 days or less in age resulting from a succession of rapid transfers appeared to be necessary for maximal growth.

Notes: SUMMARY. Great numbers of a new ameba have been collected from freshwater, lagooning, disposal tanks for citrus pulp wastes. The ameba is morphologically similar to the marine Flamella magnifica (Schaeffer, 1926), and clearly belongs to the genus. It differs sufficiently in the formation and characters of locomotor organelles, and in habitat, to be considered a separate species, Flamella citrensis n. sp.

Notes: SUMMARY. The enzymatic induction of fatty acid oxidase activity in Polytoma can be characterized as follows: (1) the preferential synthesis of oxidase activity can be induced in non-proliferating cells, (2) the rate of induction is dependent upon the concentration of exogenous nitrogen, (3) the rate of induction is also dependent upon the age of the cells, (4) with log-phase cells, the rate of synthesis is highest and the kinetics of synthesis, linear; the rate of synthesis by older cells is low and variable in form, (5) ultraviolet irradiation selectively inhibits induction at doses which do not inhibit respiratory activity, oxidative assimilation or nitrogen utilization.

Notes: SUMMARY. The trichomonad occurring in the nasal cavity of the domestic pig, Sus scrofa, is described and figured. With Heidenhain's iron-hematoxylin and protargol (protein-silver) stains, the specific characters are as follows: Pyriform in shape; length 8.8–18.4 μ (average 13.6 μ); width 3.2–8.0 μ (average 4.8 μ); blepharoplast of several granules; three anterior flagella with the longest 10.4–16.8 μ in length ending in knob-like enlargements; full length undulating membrane with four to six subequal folds and containing marginal and accessory filaments; trailing flagellum 4.8–11.2 μ in length; full length costa with fine subcostal granules; hyaline rod-shaped axostyle with bulbous capitulum, chromatic ring and conical tip; tube-like parabasal body 3.2–4.8 μ in length; oval-shaped nucleus 3.7–5.0 μ in length and 2.2–3.0 μ in width; cytostome; and vacuolated cytoplasm containing food vacuoles.Taxonomy of trichomonads in the respiratory and digestive systems of swine is discussed and the nasal trichomonad is compared with the two different forms of Trichomonas found in the cecum. The conclusion is that the nasal form is of a different species from the trichomonads of the cecum. The close similarity between the nasal form and Tritrichomonas foetus is emphasized. The writer suggests that the nasal form should not be given recognition as a new species until its true relationship with T. foetus is revealed.

Notes: SUMMARY. Saprophilus muscorum Kahl, 1931 is an edaphic species which has been identified in cultures of soil and forest litter. This ciliate has the buccal ciliary apparatus of the family Tetrahymenidae Corliss. There is only one post-oral meridian and 15 bipolar meridians, 8 of which meet ventrally at the pre-oral suture. The cilia are long and sparse and there is a prominent longer caudal cilium. Trichocysts are present. Resting or resistant cysts are formed readily.

Notes: SUMMARY. To determine whether Tetrahymena pyriformis could infect Deroceras reticulatum and become morphologically modified in the same way as the parasitic phase of T. limacis, 50 slugs were exposed for 10 days to an amicronucleate clone of T. Pyriformis and 50 were exposed for the same period of time to a micronucleate clone. The slugs were then transferred to clean containers for another 10 days, to allow ciliates which had entered the slugs either to persist and multiply or, in the case of transitory infections, to disappear. An additional 50 slugs were kept in a control group for 20 days. All of the slugs had been collected at a single locality in which natural infections by T. limacis had not been noted, and were maintained in separate one-half pint milk bottles throughout the experimental period.Of the slugs exposed to the amicronucleate clone, 40 survived to the end of the experimental period, and 15 were infected. Of those exposed to the micronucleate clone, 42 survived, and 5 were infected. Forty-three of the slugs in the control group survived, and none were infected by ciliates. In some of the slugs infected by T. pyriformis, hundreds of ciliates were noted. The infections were apparently limited to the digestive gland, intestinal tract, and fluid around the viscera. Ciliates recovered from slugs were in general smaller than those growing in thriving cultures, but morphologically were typical T. pyriformis. None were observed to have a proportionately smaller cytostome or apiculate anterior end characteristic of the parasitic phase of T. limacis.

Notes: SUMMARY. The aggregative process of Dictyostelium discoideum is unaffected by most chemical and physical alterations of the environment. Such substances as vitamins, amino acids, catabolic intermediates, purines and pyrimidines, redox poising agents, enzyme inhibitors, and inorganic salts were added to the aggregative substrate. Of these, only a few exerted any influence on aggregation except at lethal concentrations. Histidine allowed the wild-type myxamoebae to aggregate at lower population densities and accelerated the aggregative process as compared with controls on minimal agar. Brief exposure to histidine irreversibly conditioned the cells. No degradation of the imidazol skeleton was detected. A rise and fall of internal soluble histidine were demonstrable. The purine base, adenine, raised the population density required for maximal center formation.

Notes: SYNOPSIS. California ground squirrels (Citellus beecheyi) were found to be infected with trypa-nosomes whose most striking morphological features are an unusually large kinetoplast and a long, tapering posterior end. The total length is 25.2 μ, and body length is 18.0 μ. This “lewisi”-type species is compared with other trypanosomes reported from American ground squirrels, but a specific diagnosis is not made because the life cycle has not been observed and because morphological features of trypanosomes are known to vary widely under differing environmental conditions.

Notes: SYNOPSIS. The basal apparatus of the flagella and kinetoplast in Leishmania donovani have been studied with the electron microscope. The flagellar fibrils extend into the body of the protozoan to form the kinetosome. At the point of origin of the flagellum, the pellicle invaginates to form a kinetosomal vacuole around the kinetosome. The kinetoplast is formed by a transversely elongated banded structure, surrounded at some distance by a double layered kinetoplast membrane. There is no apparent connection between the kinetosome and the kinetoplast.

Notes: SYNOPSIS. Starvation of Isotricha prostoma for 72–96 hours decreased the cellular amylopectin granules and facilitated the microscopic search for bacterial feeding. I. prostoma selected and ingested only certain rods from among many types of rumen bacteria. In order to isolate the bacteria important as a food source for Isotricha, the starved protozoa were allowed to feed on mixed rumen bacteria, washed, and the crushed protozoan contents quickly cultured for bacteria. Several strains of bacteria were isolated in pure culture. Three of the rod strains isolated were rapidly ingested by I. prostoma when fed to the ciliate. In a monobacterial culture I. prostoma divided once before succumbing.

Notes: SYNOPSIS. Cultures of Trypanosoma theileri were obtained at 36° and at 37.5°C. in a blood-lysate medium inoculated with blood from three dairy cows showing subnormal milk production. The organisms were first seen after 4 days in the first subculture, reached a maximum number of about 500,000 per ml. on the 4th day of the second subculture, and attained about this same number on the 4th day of subsequent transfers. Crithidial forms predominated but trypanosomes of the blood-stream type were also numerous. Cultures were not obtained from cows with normal milk production. The infected cows, although free from helminth parasites, showed a marked eosinophilia.

Notes: SYNOPSIS. A new species of Paramecium, P. jenningsi, n. sp., from South India, is described. It is like P. aurelia except that nuclei are larger, the cell size is somewhat larger, and the macronuclear anlagen (“placentae”) have long-persisting chromatinic centers.

Notes: SYNOPSIS. The nutritional requirements of 3 isolates of Prymnesium parvum (2 Israeli, 1 Scottish) included vitamin B12 and thiamine. For comparison, 2 other brackish chrysomonads were studied: Monochrysis lutheri isolated by Droop in Scotland and Isochrysis galbana purified by McLaughlin from a culture obtained from the Plymouth laboratory.The isolates of Prymnesium parvum and Isochrysis galbana had a molecular B12 specificity like Ochromonas malhamensis: no response to Factor B, pseudovitamin B12, Factor A or Factor H. M. lutheri, in contrast, responded to pseudovitamin B12, Factor H, and Factor A.Thiamine was essential; 1.0 μg.% allowed full growth of P. parvum. The NaCl concentration for good growth was 0.3–5.0%; growth was possible from 6–12%. Dark growth was not achieved.Ammonia, as suggested from its use in suppressing outbreaks of P. parvum, was sharply inhibitory, less so at high concentrations of NaCl or at acid pH.Nitrate, ammonia, arginine, asparagine, methionine, histidine, alanine, glycine, serine, proline, leucine, isoleucine, tyrosine, aspartic and glutamic acids, acetylurea, and creatine served as nitrogen sources in both acid and alkaline media.The phosphate requirement of P. parvum and M. lutheri and Isochrysis galbana was satisfied by inorganic phosphate, commercial glycerophosphate, yeast adenylic acid, cytidylic acid, monoethyl phosphate, and riboflavin monophosphate.Laboratory cultures in defined media of the isolates of P. parvum were toxigenic to Lebistes and Gambusia. Culture fluids from alkaline media were more toxic than those from acid media, as previously noted in Israel.Culture media suitable for production of large quantities of these organisms were developed.

Notes: SYNOPSIS. Certain aspects of the metabolism of a Trichomonas batrachorum-type flagellate from the cecum of swine were studied. This trichomonad (1) oxidized glucose, mannose, maltose, sucrose, and inulin, (2) was incapable of oxidizing Krebs' cycle intermediates, (3) possessed peroxide-splitting capabilities, (4) was inhibited by only iodoacetate and arsenite, and (5) formed acid(s) aerobically. Although there was no effect on oxygen uptake, pyruvate and lactate increased the anaerobic evolution of gas(es). In addition to CO2, other gas, not absorbed by KOH, was produced anaerobically.Compared with other porcine trichomonads, the metabolism of this small trichomonad resembles most closely that of the large cecal trichomonad, T. suis. However, the smaller trichomonad had a generally lower respiratory rate, a slightly lower optimal pH, and failed to oxidize fructose, galactose, lactose, raffinose, and trehalose.

Notes: SYNOPSIS. The “dry” silver method is redescribed with special attention to the possible difficulties encountered in its use. This method first revealed the silverline or neuroformative system of the ciliates, and is considered the best method for the demonstration of this structure. The valuable results obtainable with this technique are pointed out and illustrated with appropriate photomicrographs.

Notes: SYNOPSIS. It has been assumed by others that green euglenas and derived bleached forms are physiologically equivalent except for chlorophyll and plastids. Some workers, however, have remarked upon differences which might depend on the mode of bleaching.Several hitherto undescribed chlorotic substrains of E. gracilis var. bacillaris were examined for pigment alteration, growth under a variety of conditions, and ability to withstand high temperature. These studies indicated physiological variation in the different chlorotic substrains. Although all were apparently chlorophyll-less and aplastidic, only one seemed completely achromatic. The carotenoid content of others varied. Metabolic changes manifested by altered pigmentation may reflect enzymatic variation caused by the chlorosis-inducing agents.

Notes: SYNOPSIS. Thin sections of Amoeba proteus, fixed in osmium tetroxide and embedded in methacrylate, were examined in the electron microscope. The fine structure of various protoplasmic components is described. The plasmalemma, or cell membrane, varies in thickness and structure. These variations may be due to variations in physiological state, or they may be due to differences in preparation. Along its cytoplasmic edge is always present a definite line approximately 0.01 to 0.02 μ thick. The mitochondria, or beta granules, exhibit a structure similar to that of the mitochondria of several other protozoa and comparable to that of the mitochondria of other animals. In definite association with the membrane of the food vacuole are dense, rounded particles which in size are below the limit of resolution of the light microscope. Such dense particles are much less frequently present in the hyaloplasm and in association with the plasmalemma. A possible relationship to the neutral red granules associated with food vacuoles of Paramecium is suggested. The contractile vacuole possesses a thin membrane surrounded by a much thicker circum-vacuolar zone of irregular strands which may form a three-dimensional network around the membrane. This may represent the contractile element of the vacuole. A single layer of mitochondria is closely apposed to the circum-vacuolar zone. Many small vacuoles and irregular vesicles are present throughout the cytoplasm. At times there occur groups of small, thin-walled vesicles, which may correspond to an endoplasmic reticulum. The nuclear envelope consists of a thick inner porous layer and a thinner outer layer that is continuous yet is marked by the presence of numerous small annuli, each apparently surrounding a pore. In its structure, this outer layer appears to correspond to the entire nuclear envelope of many other cell forms.

Notes: SYNOPSIS. Irradiation of Stentor coeruleus with Xray doses of 150–300 kr inhibited growth in size and fission. The irradiation also led to the development of structural abnormalities, which appeared about a day after irradiation. The inhibition of growth and fission was independent of the oxygen concentration during irradiation, but the abnormalities were produced at lower doses in nitrogen than in air. Regeneration of parts removed by cutting occurred even at the highest doses at essentially normal rate even during the period when over-all growth was completely inhibited. The conclusion is drawn that delay in fission by radiation is a secondary consequence of inhibition of growth and not a consequence of blocks in the specific morphogenetic processes required for division.

Notes: SYNOPSIS. A description is given of the formation of an unusual type of achromatic figure by two very long, narrow centrioles. The unique manner in which this structure functions in chromosomal movement is explained.

Notes: SUMMARY. The central canal of the suctorial tentacle of Ephelota is limited by a fine pellicle composed of numerous longitudinal fibrils and bearing 16–18 membrano-fibrillar ridges arranged radially in the lumen of the canal. This structure resembles that of the myonemes in the heterotrichous ciliate Stentor.The prehensile tentacle of Ephelota contains 4–6 axial protein fibers each consisting of a lamello-fibrillar bundle and isolated from one another by thin intracytoplasmic membranes.In both types of tentacle the cytoplasmic portion is immediately limited by a very thin pellicle which is continuous with the “epiplasmic membrane” and covered by the alveolar cuticle which envelops the entire body of the ciliate.

Notes: SUMMARY. A medium is described for the axenic culture of Paramecium multimicronucleatum which is chemically defined except for one constituent—a nondialyzable fraction (NDF) of an exhaustively dialyzed yeast extract. Using this medium it has been possible to demonstrate an absolute requirement for stigmasterol and the following B-vitamins: folic acid, riboflavin, thiamine and pantothenic acid. There was evidence that nicotinamide and pyridoxal are also required for continued growth of the organisms. The nitrogen requirements could be met with any of the following: proteose peptone, purified casein, crystalline ovalbumin, or a mixture of amino acids. A carbon source, in addition to that supplied by the NDF or the amino acids, was essential. Sodium acetate and sodium pyruvate would satisfy this requirement.

Notes: SUMMARY. Pleurotricha lanceolata was cultured in an aqueous extract of Cerophyl with Tetrahymena sp. as the primary food organism. It was induced to form resting cysts by crowding in the absence of food in a modified Osterhout solution. Cysts formed in this medium remained viable for several months.The morphology of the cysts and of animals undergoing excystment was studied both in the living state and in stained preparations. The excystment process was recorded by camera lucida drawings. These studies revealed no endomictic nuclear reorganization, and no extrusion of nuclear material as had been previously reported.An analysis of certain chemical and physical factors which affect excystment showed the following: the rate of excystment is temperature controlled; increasing the pH of the excystment medium increases the time required for excystment; in low concentrations some aqueous plant extracts are effective excysting agents; dilute solutions of certain plant acid mixtures neutralized with KOH are likewise effective; a number of organic substances, e.g., Bacto-yeast extract and Bacto-peptone, are also effective; and the presence of bacteria retards the rate of excystment.

Notes: SUMMARY. Measurements of the length and width of a total of 6,915 unsporulated oocysts of Eimeria necatrix from 11 infected chickens revealed a length range of 12.1-28.9 μ, width range of 10.8-23.8 μ, and a shape-index (length/width) range of 1.0-1.64. The average size range of the samples of 25-100 oocysts (mean, 66 oocysts) constituting this total and taken on the various days of the patent periods was 15.6–23.9 μ× 13.9–19.5 μ. The lengths, widths and shape indexes of the oocysts constituting such samples usually described unimodal, near-normal frequency distribution curves.The average size of oocysts issuing from an average chicken on an average day of the patent period of the infection was, with standard deviations, 19.7 ± 1.82 μ× 16.7 ± 1.20 μ. The average standard errors for the length and width were 0.237 μ and 0.158 μ, respectively, in samples of the size indicated. A tendency to increase slightly, though significantly, in size after the first three days of the patent period was noted; also, a slight, though significant, linear increase from the first to the seventh day, inclusive. A slight, though significant, tendency to shorten with the passing of the days of the patent period was detected.Analysis of variance revealed much variation in oocyst size from bird to bird on a given day and for given bird and day combinations, but significant day to day variation was demonstrated for width only. By splitting the variance during the first seven days of the patent period into its parts, it was determined that the mean oocyst size during this period was, with standard errors, 19.59 ± 0.238 μ× 16.63 ± 0.200 μ. Further analysis disclosed that a considerable reduction in oocysts measured could be accomplished, with no loss of accuracy, if fewer measurements were taken per bird and more birds were employed.

Notes: SUMMARY. Spirobutschliella clignyi, which occurs in the intestine of Pomatoceros triqueter, was found in numbers ranging from 1 to 98 in about 45% of the host specimens examined at Drøbak. Comparative incidence of infection in closely neighboring host specimens suggests that migration of normal sized ciliates is not the main route of infection. The distribution of dwarf ciliates indicates the possibility of their being involved in transmission. The general morphology and the absence of skeletal structures would seem to permit inclusion of the species in the family Anoplophryidae.

Notes: SUMMARY. Three enzymes of the glycolytic pathway, hitherto not identified in Trichomonas vaginalis, have been studied: phosphoglucomutasse, α-glycerophosphate dehydrogenase, and lactic dehydrogenase.The identification of seven phosphorylated glycolytic intermediates is reported.The operation of glycolysis in T. vaginalis is postulated from enzymatic as well as chemical studies.

Notes: SUMMARY. Sodium pyruvate, glutathione, potassium cyanide, dextrose, sucrose, 3 nucleic acid derivatives, 11 B-vitamins, and 22 amino acids were tested for their ability to protect Astasia longa against the lethal damage induced by ultraviolet radiation. Compounds which protected when added to a cell suspension just before irradiation were cystine, phenylalanine, tryptophan, tyrosine, adenine, cytidylic acid, uracil, and sodium pyruvate. None of these compounds protected when added immediately after irradiation. Except for phenylalanine, solutions of these compounds afforded protection when used as filters between the ultraviolet source and the flagellates. Cysteine failed to protect when added just before irradiation, but gave good protection when cells were grown in its presence.

Notes: SUMMARY. The number of complete primary ciliary meridians in Tetrahymena limacis found in natural infections in the slug Deroceras reticulatum has been observed to range from 32 to 40. To study the range in the number of meridians in clones in culture, 10 ciliates were pipetted singly from each of two natural infections into sterile 1% (w/v) yeast extract to which 400 units of potassium penicillin-G and 500 micrograms of dihydrostreptomycin sulfate per ml. had been added aseptically. Ten ciliates were also pipetted from each of these natural infections into infusions of tissue of the digestive gland of D. reticulatum. Altogether, 28 clones (13 axenic clones in yeast extract and 15 bacterized clones in tissue infusions) were established.The shape of ciliates in thriving axenic cultures is generally ovoid or pyriform, and similar to that of ciliates in bacterized cultures. However, ciliates in axenic cultures are sharply apiculate at the anterior end and free from inclusions other than small lipoid granules, and in these respects resemble ciliates of the parasitic phase. The cytostome of ciliates in bacterized and axenic cultures is larger in proportion to the size of the body than it is in the parasitic phase.The ranges in the number of ciliary meridians in ciliates of the two natural infections from which the clones were established were 33 to 40 and 32 to 38, whereas the number of meridians in the clones taken as a whole ranged from 25 to 32. Fifteen of the clones showed extremes of 26 and 30.One of the clones was re-introduced into D. reticulatum by exposing 50 slugs to a culture of the ciliates for 10 days. The slugs were then transferred to clean containers for another 10 days. Forty-one of the slugs exposed to ciliates survived the experimental period, and 32 became infected by T. limacis. Forty-four of 50 slugs in an unexposed control group survived, and none were infected by ciliates. In the ciliates from slugs of the experimental series, the number of complete primary meridians ranged from 28 to 36. However, more than half of the ciliates in the experimental infections possessed incomplete rows, and some individuals had as many as five of these. Ciliates in natural infections and in cultures sometimes have incomplete rows, but rarely show more than one such row. The incomplete rows in ciliates re-introduced into slugs are considered largely to be incipient segments of future complete rows. They occur most commonly in the post-oral region, and particularly between row 1 (the so-called stomatogenous meridian) and the next complete row to the observer's right. It appears, therefore, that the post-oral region is a zone in which most new rows are proliferated.

Notes: SUMMARY. Manometric and culture experiments were designed to study factors influencing the metabolism of Trichonympha from Zootermopsis. A starvation period of 36–44 hours for the termites lowered the endogenous metabolism of Trichonympha and made possible the testing of substrates in the Warburg apparatus. In the presence of antibiotics, cellulose and cellobiose were utilized at approximately the same rate by the protozoa. Yeast extract stimulated cellulose fermentation in Trichonympha from starved termites, but the effect could not be demonstrated in protozoa from recently fed termites. Yeast extract, blood serum, and liver fractions improved the survival of the flagellates in anaerobic cultures.

Notes: SUMMARY. The peduncle of the chonotrichous ciliate Chilodochona is composed of a bundle of protein fibers secreted by intracytoplasmic glandular ampullae. This process, very different from that involved in production of the peduncle in the peritrichous ciliates, also is found, although with a simpler result, among the Dysteriidae, a highly evolved family of gymnostomes closely related to the chonotrichs.

Notes: SUMMARY. A new actinomyxid, Triactinomyxon naidanum, distinguished from other members of the genus by having 12 sporoplasms, is described from the intestine of an Indian fresh-water oligochaete, Nais communis punjabensis. This is the first finding of an actinomyxid in Asia and also the first finding in a member of the family Naididae.

Notes: SUMMARY. A new species of Tetrahymena is described, the ninth to be allocated to this genus. Most significant morphologically and taxonomically is its possession of a single, slender caudal cilium, twice the length of the surrounding somatic ciliature. The presence of this inconspicuous organelle, quite novel to the genus, is also detectable in the infraciliature where an argentophilic “polar basal granule-complex” appears exactly at the posterior pole of the body. The diagnosis of the genus Tetrahymena is expanded to embrace species with such a caudal appendage.

Notes: SUMMARY. Ciliates referable to Tetrahymena limacis have been found in two native terrestrial pulmonates, Monadenia fidelis (Helicidae) and Prophysaon andersoni (Arionidae), collected in Oregon. The number of complete primary meridians in ciliates in natural infections in M. fidelis has been observed to range from 26 to 32, and the number in ciliates in P. andersoni has been observed to range from 37 to 41. T. limacis from the European Deroceras reticulatum (Limacidae) has shown a range of 32 to 40 meridians. From 20 ciliates pipetted from a single natural infection in M. fidelis into either 1% (w/v) yeast extract (with antibiotics) or an infusion of digestive gland tissue, 16 clones were established successfully. The range in the number of meridians in these cultured ciliates was 24 to 29; eight clones showed a range of 24 to 28. Sixteen clones established in the same way from ciliates taken from P. andersoni showed a range of 26 to 32 meridians; ten clones had a range of 27 to 31. The range in the number of meridians observed in earlier studies of 28 clones established from ciliates from two natural infections in D. reticulatum was 25 to 32.To determine whether the ciliates from the native pulmonates have a strong host specificity, 50 D. reticulatum were exposed for 10 days to a clone derived from M. fidelis, and 50 were exposed to a clone from P. andersoni. For comparative purposes, 50 slugs were exposed to a clone derived from D. reticulatum. An additional 50 slugs were maintained in a control group. Ten days after the end of the period of exposure, all of the surviving controls (47) and 25 of the slugs in each group exposed to ciliates were examined for infections. The remainder of the surviving slugs in each group were examined 20 days after the period of exposure. Successful experimental infections were noted in each of the groups of slugs exposed to the three clones, and the ciliates in the infections were typical of the parasitic phase of T. limacis. None of the slugs in the control group were infected. Ten days after the period of exposure, the range in the number of complete primary meridians noted in the experimental infections, taken as a whole, by ciliates of the clones from M. fidelis, P. andersoni, and D. reticulatum were, respectively, 26 to 33, 26 to 37, and 29 to 37. The ranges for ciliates in infections by these same clones 20 days alter the period of exposure were 26 to 33, 29 to 37, and 28 to 36. Incomplete rows, up to five in number, occurred in ciliates in experimental infections by each of the clones, but the addition of the number of incomplete meridians to the number of complete meridians did not influence the maximums, except in the case of some infections by the clone from M. fidelis in which a few ciliates showed a total of 34 meridians. It appears that although T. limacis from the native pulmonates will readily infect D. reticulatum, the ciliates from P. andersoni do not attain, at least under the conditions of the experiments which have been conducted, a number of rows exceeding the minimum number of 37 noted in natural infections in P. andersoni.

Notes: SUMMARY. The effect of surface-active agents on the permeability, survival, and pseudopod formation of the rhizopod, Pelomyxa carolinensis, was studied. Surfactants increased the rate of uptake of Na22 in almost all instances. Tweens which lower surface tension, stimulated or caused pseudopod formation; Tween 80 was the least toxic. The fatty acid component as well as the hydrophile-lipophile balance of the surfactant may influence the rate.

Notes: SUMMARY. A small ameba found both in rocky tide pools and tide washed sand is described. It is widely distributed, having been collected in both Pacific and Gulf of Mexico waters. The ameba extends clear, conical pseudopods which wave prior to retraction. It is presented as Vexillifera telmathalassa n. sp., in the Family Mayorellidae, Order Amoebida.

Notes: SUMMARY. At any given temperature level, the rate of oxygen poisoning increases proportionally with an increase in oxygen tension. But the toxicity of oxygen does not bear a proportional relationship to temperature. At a constant low tension, it is more toxic at low temperatures than at high ones and, at a constant high tension, it is less toxic at low temperatures than at high ones.

Notes: SUMMARY. Washed intact cell preparations of T. vaginalis oxidize pyruvate and malate. They are unable to utilize other intermediates of the Krebs cycle. Homogenates of these cells show the same pattern of enzymatic dehydrogenase activity toward the Krebs cycle organic acids. Attempts to inhibit pyruvate oxidation with such Krebs cycle blocking agents as malonate, arsenite, parapyruvate, and fluoroacetate were unsuccessful.Isotopic tracer studies with 2-C14 pyruvate showed that although several, as yet unidentified, compounds incorporated activity during the course of pyruvate metabolism, none of these labeled compounds corresponded to any of the Krebs cycle intermediates.It is concluded that the Krebs cycle is not the pathway for the oxidation of pyruvate in T. vaginalis.

Notes: SUMMARY. Chromosome behavior of strains WH-6, and WH-14 mating types I and II respectively of variety 1, of T. pyriformis was studied during conjugation. Meiosis takes place during the first two prezygotic divisions. The chromosomes are at late pachytene-early diplotene during the maximum elongation of the crescent in prophase of the first micronuclear division. As the crescent shortens, five bivalent chromosomes are readily recognized. Five dyads go to each pole at the end of the first division. Following a brief interphase the second meiotic division results in four micronuclear products, each with five chromosomes. Three of these products disintegrate; the fourth undergoes mitosis resulting in two pronuclei each with five chromosomes. Following a reciprocal interchange of the migratory pronuclei between the two conjugants, the synkaryon of each is formed just anterior to the macronucleus. The diploid number of ten chromosomes has been counted at the first division of the synkaryon.

Notes: SUMMARY. Isolated Blepharisma undulans were studied for the following: (1) fission rate, (2) mating behavior, (3) giant formation, (4) effects of daily transections. The organisms were maintained at 22°C. and isolated daily for 60 days. Fission rate varied from two divisions a day to one in 29 days. The major factor producing the variation appeared to be the type or amount of food. Frequency of conjugation also varied greatly. Daughters of a single organism will mate within 24 hours after division. Conjugation followed by one division, re-isolation, then conjugation within 24 hours following a second division occurred within a 5 day period. Giants were produced within 3 days by feeding with Khawkinea, Chilomonas and Paramecium. Paramecium alone did not produce giants. Exposure to 10−m, 10−4M colchicine did not accelerate this process.Daily transections into approximately equal halves were made. The anterior halves containing the mouth membranelles were followed. Fission rate was not affected by cutting. A progressive decrease in size occurred. All ultimately lysed, most on the 7th day. If cutting was suspended on any day, recovery and fission followed. If cutting was re-instituted, lysis would again occur on or about the 7th day. Daily amputation of the posterior tip for 2 weeks did not affect either size, fission rate, or longevity.

Notes: SUMMARY. Frontonia depressa (Stokes) Penard is an edaphic species characterized by formation of cysts. There is no dedifferentiation of the ciliate when encysted, and all organelles, except the body cilia and buccal apparatus, are clearly visible. Excystment is dependent upon the building up of hydrostatic pressure by the contractile vacuole. Activation is not always followed by excystment, which takes some hours.

Notes: SUMMARY. As part of an extended series of experiments, various combinations of primaquine-pyrimethamine were tested against pigeons infected with Plasmodium relictum.(a) Rapid clearance of blood forms was observed, although each component had been reduced to one-half of its previously established MED (minimal effective dose) for such clearance when administered alone.(b) Primaquine-pyrimethamine was followed by unprecedented delays in relapse after drug withdrawal. Such delays had not been elicited in any previous experiments in the series, employing each component alone, or chloroquine alone, or primaquine-chloroquine combinations, or pamaquine-plasmocid-chloroquine (Premaline N).

Notes: SYNOPSIS. Crosses between serine requiring and non-requiring clones from natural habitats give rise to progeny that are numerically equally distributed between the two categories. Most of the progeny from crosses between two serine requiring parental clones require serine with a few segregating out that do not need the amino acid. These data indicate that the gene or genes controlling the serine non-requirement are recessive to the wild type which requires serine. Growth of the F1 progeny was highly variable. Some clones failed to survive on serine deficient media and were therefore tentatively assigned the genotype +/+. The remaining clones were of two classes: one grew slowly on serine deficient media and was given the genotype of the heterozygote, +/s; the other grew without serine, hence was given the double recessive genotype, s/s. The F2 progeny from matings of s/s and s/s need no serine whereas the cross of +/s and s/s gave equal numbers of serine requiring and serine non-requiring progeny. The cross of two heterozygotes, +/s and +/s, yield progeny approximating the 3:1 ratio in favor of serine requiring clones. Crosses at the F3 level produced non-viable offspring in all cases except one. Progeny from this cross with the genotype s/s were mated giving rise to F4 progeny all of which grew without serine. The data support an outbreeding economy for this organism with selection in favor of the heterozygote. Although the data seem to favor a single-gene hypothysis, suppressor genes may be involved. With selection favoring the heterzygote, distorted genetic ratios make the data difficult to analyze.

Notes: SYNOPSIS. Intracardial inoculation of 1–10 million L. donovani in 0.1 ml. of ground spleen suspension from an infected animal (hamster) results in a uniform rise of parasite numbers in the untreated animal over the first 8 days after the inoculation. This rise is highly consistent from experiment to experiment.Treatment is accomplished by parenteral injection of a compound for 6 successive days in this time interval, starting 24 hours after inoculation.No known active compound in proper dosage (sodium stibogluconate, pentamidine, fuadin) has failed to show a significant suppression of the expected rise in parasite numbers. No known inactive compound has had any effect on the course of the infection.The dosage-response curve for the active compounds suggests that the method is a sensitive one. Since it takes only 8 days to complete, it is economical as well.

Notes: SYNOPSIS. It has been shown that the output of the contractile vacuole of Crithidia fasciculata increases as the concentration of solute in the external solution decreases when NaCl is the solute. The increase in output is the result of increased rate of growth as well as increased maximum size, the latter being more important in the range 0.1M–0.01M. Solutions of penta-erythritol produce the same effects as isosmolar solutions of NaCl. Body volume is not maintained constant but increases less than two-fold between 0.1M and 0.0001M. The isotonic concentration of NaCl is estimated as 0.12M. It is not possible to demonstrate any effect of concentration of the external environment on the endogenous rate of oxygen consumption. A linear relationship between output and calculated osmotic gradient across the cell membrane has been shown in the concentration range 0.1M–0.01M. Absence of this relationship, and failure of body volume to increase as predicted, in solutions more dilute than 0.01M are interpreted as indications that other processes probably become predominant in these solutions. It is concluded that the contractile vacuole of this flagellate is incapable of maintaining absolute constancy of internal osmotic pressure and body volume but prevents much of the change expected on physical grounds.

Notes: SYNOPSIS. The rather rarely found holotrichous ciliate Pseudomicrothorax dubius, generally considered in the most authoritative literature to be a member of the order Trichostomatida, more likely belongs in the Hymenostomatida. Its curious combination of trans-ordinal characteristics, however, makes difficult exact systematic allocation of it and of the congeneric species P. agilis. The provocative morphological features include: a gymnostome-like cytopharyngeal “basket”; a tetrahymenal buccal apparatus, with membranelles comparable with those of primitive hymenostomes; an advanced semi-autonomous type of stomatogenesis; and sensory bristles, flattened rigid form, and restricted ciliature reminiscent of certain spirotrichs. Brief discussion is presented concerning the influence of modern ideas of ciliate classification upon what is considered the proper taxonomic position of the genus.

Notes: SYNOPSIS. A new fresh water species of Actinosphaerium is described, the fourth member of the genus. Some of the more significant of its diagnostic traits are: 1) the Actinophrys-like nuclei with peripheral nucleolar granules and without central rosette-shaped nucleoli, 2) the occurrence of some nuclei in the ecto-endoplasmic border and the insertion of axial filaments on them, and 3) the low ratio of endoplasm to ectoplasm.

Notes: SYNOPSIS. In cultures of the marine dinoflagellate Gonyaulax polyedra grown with alternating light and dark periods of 12 hours each, at least 85% of all cell divisions which occur in a day take place during a 5-hour period spanning the end of the dark period and the beginning of the light period. A very distinct maximum in the number of recently divided cells occurs at about the time the light period begins.This diurnal periodicity in cell division is lost after 4 to 6 days in continuous bright light, but will persist for at least 14 days in continuous dim light. The period of approximately 24 hours under constant conditions is only slightly altered by varying light intensity and temperature, both of which factors are known to affect markedly the generation time. The time at which cell division occurs is therefore postulated to be controlled by some sort of rhythmic or clock mechanism.Similarities between the cell division rhythm and the endogenous rhythm of luminescence in this organism are discussed. The occurrence of a glow, or steady light emission of low intensity, at about the time of cell division, is described, and it is suggested that this glow may result from cellular changes accompanying certain stages of cell division.

Notes: SYNOPSIS. The photographs illustrate male and female gametes before fertilization, several progressive stages in the entrance of the male gamete into the cytoplasm of the female, cytoplasmic fusion of gametes, loss of extranuclear organelles of male gamete, retention of extranuclear organelles of female gamete, movement of pronucleus of male gamete to that of female, progressive stages in fusion of pronuclei, and the formation of the zygote which possesses the extranuclear organelles of the female gamete. Some abortive attempts at fertilization, resulting from failure of gametes to differentiate, are shown.

Notes: SYNOPSIS. Detailed directions are given for the preparation of a simplified assay medium and of natural materials for assay of pteridines with Crithidia fasciculata. Unconjugated pteridines in natural materials which also contain conjugated pteridines (folic and folinic acids) can be assayed by destroying the conjugated pteridines with acid hydrolysis, which does not appreciably alter Crithidia-active unconjugated pteridines. The widespread occurrence of unconjugated pteridines and their significance in such processes as photoreception are discussed.

Notes: SYNOPSIS. Photokinesis or the non-directed rate of swimming of Euglena gracilis for various light intensities was studied. The rate of swimming in white light was found to increase with light intensity until it reaches 0.16 mm./sec. at a saturation of 40 ft. candles, and then decreased with increasing light intensities. Polarized light appeared to be more effective (0.18 mm./sec. at 13 ft. candles) than non-polarized light.The action spectrum for photokinesis showed two peaks, a major one near 465 mμ, and another in the neighborhood of 630 mμ, having the values of 0.18 mm./sec. and 0.16 mm./sec. respectively at an intensity of 4 ft. candles.The action spectrum for phototaxis, or directed orientation, had a peak near 420 mμ and showed a maximum near 490 mμ. Both dark-grown and dark-adapted Euglena showed spectral peaks similar to those of the light-grown cells. For polarized light, the action spectrum had two additional peaks at 468 mμ and 508 mμ. The polarized light effect may indicate more than one light-absorbing pigment within the “eye spot” or that other pigments within Euglena were absorbing.

Notes: SYNOPSIS. Four new species of Eimeria are described from small mammals in Liberia. These are: E. levinei, sp. nov. from a free-tailed bat, E. firestonei, sp. nov., and E. milleri, sp. nov., from a shrew, and E. putevelata, sp. nov., from a striped grass mouse.

Notes: SYNOPSIS. A new species of Stentor is described, a fresh water form, medium sized, with cerulean blue pigment, and characterized by retractable feeding organelles.

Notes: SYNOPSIS. Coprozoic protozoa from elk, bison, bear, moose, coyote, marmot, cattle, horse, sheep and man were kept in feces at 4° C. for 2–6 months. During that time in most of the samples there developed the flagellates Cercomonas sp., Copromonas ruminantium and Monas communis; the amoebae Vahlkampfia sp. and Sappinia diploidea, and ciliates of the Nyctotherus type, and an unidentified smaller species. There was a correlation between numbers of protozoa and bacteria. The same species of protozoa in soil or in soil mixed with boiled feces failed to live. Coprozoic protozoa may require certain essential metabolites from bacteria as do true parasites. The wide variation in appearance of cysts made it practically impossible to identify the protozoa with certainty in that stage. Reliance had to be on motile forms which readily developed in the cold cultures.

Notes: SUMMARY. Vegetative clones of Tetrahymena pyriformis, variety 2, mating type II, were the recipients of various dosages of X-rays from 10,000 to 400,000r. One clone from the 400,000 level (UM7X), when mated with non-irradiated cells of various mating types in variety 2, failed to produce a migratory nucleus. A one-way transfer from the normal to irradiated mate occurred, resulting in the production of haploid exconjugants.When haploids were crossed with diploids the former failed to produce a migratory nucleus. A one-way nuclear transfer from the diploid to the haploid occurred resulting again in the production of haploid exconjugants. When two haploids were crossed a clone resulted which showed 80 to 90 percent amicronucleate forms.The mating type of the derived haploid is always that of the diploid parent. All derived haploids manifest physiological and morphological characteristics similar to those of the diploid except that the haploids possess a smaller micronucleus.

Notes: SUMMARY. The structural morphology of Euglena gracilis, particularly the photoreceptors, has been studied by electron microscopy in order to arrive at some structural basis for function. The chloroplast, eye-spot, and flagella are described and their relationship within the cell discussed. A molecular model for both the chloroplast and eye-spot are proposed from the available structural and experimental data. The effects of darkness, elevated temperatures, metal depletion, and streptomycin on the cells and structure of the chloroplast are described. In all cases where structural changes occur in the chloroplast they are accompanied by spectral shifts in the absorption spectra of chlorophyll indicative of the appearance of pheophytin. The relationship of the eye-spot and flagella was considered as a structural unit and the energy for excitation was roughly estimated.

Notes: SUMMARY. The characteristics of Plasmodium lophurae infections in mice have been studied for a period of 3 years. The average height of parasitemias increased steadily for several months then leveled off with but minor changes for the remainder of the time. Gametocytes were found during the ninth month after the passages were begun. Comparison of the strain after 3 years in mice with the same species of parasite maintained constantly in chick embryos indicated that the sojourn in the mouse had temporarily disturbed the mean numbers of merozoites produced.