ALBERT

Notes: Amicronucleate (strain W) and micronucleate (strain HAM 3) Tetrahymena pyriformis have been studied by light and electron microscopy. Numerous interphase and individually-sectioned organisms in division stages have been examined. In macronuclei of the amicronucleate organisms (strain W) the time of division is characterized by a rather marked chromatin condensation, by morphological changes in nucleoli, and by the presence of dense granules. In macro-nuclei of the micronucleus-possessing organisms (strain HAM 3) little alteration of the interphase morphology is observed at division. Mitochondrial changes and an increase in the amount and complexity of the endoplasmic reticulum are observed in division in the amicronucleate strain. These results show that macronuclear division is more complex than a simple “pinching-in-two” and that loss of the micronucleus may alter the mitotic events of the macronucleus.

Notes: Nitrogen in cell fractions of Paramecium aurelia varied according to the growth medium. Trichloroacetic acid-soluble fractions of cells were chromatographer. Adenine, adenosine, guanine, guanosine, hypoxanthine, aspartic acid, glutamic acid, histidine, lysine, proline, and phenylalanine were identified. Fyrimidines and xanthine, or their respective ribosides and ribotides, were not detected. Ammonia was released into the medium by both actively growing and “resting” cells. Culture fluids of “resting”cells also contained hypoxanthine and lesser amounts of adenine and guanine. Urea, uric acid, creatine, cretonne, and ailantoin were absent.Pyrimidine nitrogen seems excreted as dihydrouracil. The following enzymes were detected in homogenates and cell-free preparations: nucleotidases, nucleoside hydrolases, and cytidine deaminase. Urease, uricase, adenase, guanase, xanthine oxidase, adenosine deaminase, and 5′-adenylic acid deaminase were not present in this organism.Purine and pyrimidine incorporation into nucleic acids was investigated by the use of radioactive tracers. Guanosine gives rise to nucleic-acid guanine and adenine; adenosine was precursor to nucleic acid adenine only. Formate was incorporated into purines; glycine was not. P. aurelia can interconvert cytidine and uridine; both give rise to nucleic acid thymine. The methyl group of thymine may be derived from formate.

Notes: The slime mold Fuligo septica has been grown bacteria-free in a pure 1.5% agar and oats at a temperature of 25°C. The Plasmodium was also grown under water.

Notes: SYNOPSIS. Chilomonas paramecium has been studied by light and electron microscopy with special attention to the so-called trichocysts. The electron miscroscope reveals that the anatomy of these bodies is unlike that of the classical trichocysts of ciliates. Since these structures can be extruded from the body of the organism they have been called ejectisomes. The ejectisomes have a regular geometrical shape and a complex internal structure. They consist of two unequal components which are enclosed by a thin membrane. Morphological polarity is established by an anterior smaller unit and a posterior larger unit. When the ejectisomes are found in the peripheral cytoplasm or in a perivestibular position the smaller unit is always oriented toward the surface. A suggestion is made that the ejectisomes are derived from the vesicular component of the Golgi complex. An interpretation is offered concerning a mechanism by which ejectisomes may be extruded from the body.

Notes: SYNOPSIS. Examination of the crop, gizzard, and intestinal contents of chickens fed suspensions of either Eimeria acervulina or E. tenella oocysts and turkeys fed either E. meleagrimitis or E. gallopavonis oocysts indicated that, in all 4 species, (1) oocysts apparently remained unchanged while in the crop, (2) sporocysts were liberated from oocysts while the latter were passing through the gizzard, (3) sporozoites were activated and escaped from liberated sporocysts after they had reached the small intestine, and (4) sporozoites within intact oocysts in the crop, gizzard, and intestines were not activated. In vitro, trypsin 1–300 alone caused a small percentage of sporozoites to excyst from mechanically liberated sporocysts. The percentage of excystation increased greatly when trypsin was added to sodium taurocholate and increased even more when it was combined with chicken or turkey bile.The two duodenal species (E. acervulina and E. meleagrimitis) differed both in vivo and in vitro from the two cecal species (E. tenella and E. gallopavonis). The duodenal species excysted in less time and farther anteriorly in the small intestine than did the cecal species. In addition, sporozoites of the two cecal species survived much longer in media containing trypsin plus bile or sodium taurccholate than did those of the two duodenal species.

Notes: SYNOPSIS. Cysts of the hypotrichous ciliate Pleurotricha lanceolata were placed in dilute aqueous solutions of specific chemicals (carbohydrates, vitamins, L-amino acids, nucleic acids and derivatives, other organic acids and tweens) to assay the effectiveness of these chemicals as excysting agents. It was found that some of the amino acids, deoxyribonucleic acid, ribonucleic acid, and some other organic acids induce excystment at rates equal to or better than the control medium, 0.05% (w/v) aqueous lettuce extract. Preliminary experiments with chelating agents, tri- and tetra-sodium salts of ethylenediaminetetraacetic acid (Versenol 120 and Versene 100), indicate that they successfully initiate excystment, but support it inadequately thereafter so that most of the organisms die within the endocyst.

Notes: SYNOPSIS. A new species of avian malaria parasite is described, for which the name Plasmodium formosanum is proposed. It was observed in the blood of Arboriphila crudigularis, the Formosan hill partridge; other bird species in which it may occur remain unknown, as do the mosquito vectors. It produces very broad, elongate gametocytes, the macrogametocyte usually exhibiting a very large vacuole. The usual number of merozoites is eight. The host cell nucleus typically is not displaced, except laterally by the sexual forms. Only the stages occurring in the blood have yet been seen.

Notes: SYNOPSIS. Three chlorotic Euglena substrains, PBZ-G4, SM-L1, and HB-G, were cultured in light and dark at 25° and 33–35°C. These permanently chlorophyll-less flagellates with different carotenoid distributions were originally derived from a photosynthetic stock culture. Astasia longa, a naturally pigmentless flagellate, and the ciliate Tetrahymena were also employed.None of the organisms were light-dependent at 25°C. At high temperatures only the Euglena substrains showed an effect of light on growth: PBZ-G4 was inhibited, as was the photosynthetic parent strain, whereas SM-L1 and HB-G were stimulated. In all three substrains, monster forms were produced at elevated temperatures; SM-L1 and HB-G were multinucleated, while PBZ-G4 had an enlarged, single nucleus. A small percentage of astasias became multinucleated and almost all the tetrahymenas became giants when cultured at high temperature but neither was affected by light.Light-temperature interactions in the nonphotosynthetic substrains of Euglena are, at present, unexplained. The results are discussed in relation to the carotenoid content and the possible site of interaction. The major factor inducing abnormality is thermal stress.

Notes: SYNOPSIS. Ophryoglena faurei is a large ophryoglena distinguished by a long theront, either cylindrical or pearshaped, by a very bulky, often lengthened trophont and by a voluminous tomont.During fasting, physiological changes cause a secondary and temporary encystment of the theront which lasts for 15–18 days at 18°C. Then the theront becomes globular and cytolyzes. Feeding induces the usual physiological reproductive cycles. Production of 4 and 8 tomites is the result of primary cycles happening before secondary encystment. The secondary cycles induced by feeding of the secondary theront, after its encystment, are characterized by the production of 2 or 4 tomites.If the theront is fed after being starved for about 10 days the resultant trophont encysts and delivers only one theront. The size of this theront is the more reduced as the starvation of the original theront has been longer. The small theronts are able to attain the original major forms but only after several successive alimental cycles and without any secondary encystment of theronts.

Notes: SYNOPSIS. Comparison of dimensional and other morphological details of adult suctorians recovered from the gills of five genera of fish from five widely separated localities in North America indicates that the practice of identifying a distinct suctorian species based upon the species of fish with which it is symbiotic is unfounded. Conversely, identification of suctorian species based on their adult morphology alone under certain conditions is justified. An emended diagnosis of Trichophyra piscium Bütschli, 1889, is presented. The pigment in T. piscium recovered from Oncorhynchus nerka (sockeye salmon) was characterized as melanin and its significance to the suctorians is discussed.

Notes: SYNOPSIS. An isosporan morphologically identical to Isospora crotali (Triffitt), 1925, was found in fecal material from one of six Florida diamond-back rattlesnakes, Crotalus adamanteus. It is the only coccidian parasite found in a survey of over 200 feral snakes, including individuals from 4 families, 43 genera and 65 species. The endozoic sexual phases of the life-cycle occur in the epithelial cells of the jejunum of the snake, as does formation of oocyst and sporocyst. Sporozoite formation occurs ectozoically, the sporulation time being 17 hr from onset of sporoplasmic fission, with a range of 13 hr. A survey of the literature indicates that I. crotali is probably the same species as the later described I. dirumpens Hoare, 1933, which has a widespread geographic distribution in diverse species of snakes. Other organisms probably synonymous with I. crotali include I. fragilis, I. laverani, I. lenti, and I. naiae. Reports of isosporan infections in snakes are few, particularly in the feral animals.

Notes: SYNOPSIS. A new peritrichous ciliate, Epistylis helicostylum n. sp. is described. It lives attached to the extremities of the ostracod Eucypris virens as its specific symphoriont. A spiral structure forming a protective theca for the colony of daughter animals is produced by the allometric growth of the outer sheath of the stalk. The whole process of its formation is described.

Notes: SYNOPSIS. Novel serotypes appeared among the F2 progeny of a single cross involving alleles at the H locus. Two of the clones manifesting aberrant types have been subjected to breeding analysis. The aberrant phenotypes disappear at conjugation and have not been recovered in either F1 or F2. Comparable types have not been found again in large scale crosses involving a variety of different H alleles. The basis for the unusual types remains obscure.

Notes: SYNOPSIS. Inhibitory activity of a series of drugs has been tested against Trichomonas vaginalis pour-plated in agar. Drugs were applied in impregnated paper discs on the surface of the agar and activities determined by the presence of surrounding zones without growth. Control discs without drug showed no inhibition of the flagellate's growth.Some relationships of structure to activity were found in a group of substituted nitroimidazoles and nitrothiazoles. Diamidines, except for one with a triazene nucleus, produced little or no effect. Antibiotics varied from very high activity to none; a group of miscellaneous compounds, not quite so widely. Among the antibiotics, thiolutin merits further study as a possible biotin antagonist. Three closely related drugs, one of them known to inhibit cholesterol synthesis in mammals and Protozoa, restricted growth of T. vaginalis.Suggestions are made as to further uses of disc or strip tests with plated trichomonads for studies of nutrition, metabolism, and genetics.

Notes: SYNOPSIS. In cultures of Poteriochromonas stipitata the growth of which was inhibited by urethan the deoxyribosenucleic acid-nitrogen fraction was affected most. Thymine and some of its postulated precursors prevented this growth inhibition.

Notes: SYNOPSIS. Using intervals up to 5 hours, attempts to excyst sporozoites of Eimeria acervulina from intact oocysts in vitro were unsuccessful.Examination of crop, gizzard, and intestinal contents of chicks fed large numbers of sporulated oocysts indicated that (1) no obvious change in the oocysts occurred in the crop, (2) a high percentage of the sporocysts were quickly released from the oocysts in the gizzard, (3) the sporozoites escaped from the liberated sporocysts in the duodenum and jejunum, and (4) the action of the digestive juice was apparently on the sporocysts rather than on the oocysts. In vitro attempts to excyst sporozoites from free sporocysts with various pancreatic preparations in the absence of bile produced low or insignificant percentages of excystation. In the presence of bile, bile salts, and other surface-active agents, the action of the pancreatic preparations was greatly increased. The heaviest suspension of motile, nonaggregating sporozoites was obtained with 0.25% trypsin 1–300 in 5% chicken bile at pH 7.6.

Notes: SYNOPSIS. The oral apparatus of the gymnostome ciliate Chlamydodon pedarius is composed of a membranous system, a pharyngeal basket and pharyngeal tube. The membranous system outlines the cytostome; its outer part is connected with the pellicular and sub-pellicular membranes, forming a circular groove along the outer margin of the cytostome; its inner part bends and extends to the cytopharynx, forming an oral cavity. The membranous system consists of a membrane combining the pellicular and sub-pellicular membranes and just beneath it is a layer of randomly intertwining filaments about 20 mμ in diameter. The pharyngeal basket is composed of triangular trichites and long ones. They are normally 11 to 13 in number. The triangular trichites are connected with the long ones by fibers. Each of the triangular trichites has a quasi-conical form, about 1.5 μ in width at its basal portion and about 2.5 μ in height, and is made up of an outer dense sheath and a central less dense part. Each of the long trichites is whip-shaped and extends into the endoplasm for about 35 μ. They surround the pharyngeal tube, and their posterior ends are gathered into a triangular or a circular form by means of a fiber. Each of the long trichites consists of a bundle of about 700 filaments arranged in an almost hexagonal pattern. Each filament is about 20 mμ in diameter and seems to be linked with others by six fine fibrils. The pharyngeal tube is composed of lamellae about a hundred in number. The lamellae are about 30 mμ in thickness and about 40 mμ apart from each other. The substance of the lamellae appears to be largely-structureless, although some very fine, short fibrils randomly arranged can be distinguished in longitudinal sections.It is concluded that the component parts of the oral apparatus may come from different origins. Each of the long trichites composing the pharyngeal basket may originate from about 80 kinetosomes, and the lamellae composing the pharyngeal tube and the membranous system may arise from the sub-pellicular membrane.

Notes: SYNOPSIS. The reproduction of Toxoplasma gondii has been investigated in osmium fixed and sedimented mouse peritoneal exudate. The material was obtained 9 days after intraperitoneal inoculation with the Beverley strain. Predominantly intracellular organisms were seen in various phases of multiplication and indicated the occurrence of three different modes of reproduction. One is a schizogonic cycle, whereby at least four progenies are delineated within a rosette-shaped, multinucleated Toxoplasma cell. They subsequently separate to become individual parasites. The second mode is considered as a special type of schizogony that results in the production of only two merozoites within one parent cell. This process previously has been designated as endodyogeny. Finally, the observations suggest division by binary fission as a third type of reproduction.From these results, it is possible to relate the genus Toxoplasma, previously regarded as a protozoon of uncertain classification, to the class Sporozoa.

Notes: SYNOPSIS. Rabbit antisera to trophic and resting cyst stages of C. maupasi were analyzed by absorption and cross absorption with trophic and resting cyst antigens. The trophic form gave rise to immobilizing and agglutinating antisera of high titer, whereas the cyst stage gave rise to immobilizing and agglutinating antisera of lower titer. The cyst antiserum also stimulated the formation of a gelatinous membrane around some of the immobilized organisms. Both antisera had their effect against the trophic form; the cyst stage was not visibly affected.Two antigenic components were demonstrated in the resting cyst stage, one shared in common with the trophic stage, which gave rise to an immobilizing and agglutinating antibody, and a second antigen present only in the cyst, yielding a lytic antibody. The lytic antibody was revealed only after absorption of the immobilizing antibody component from the cyst antiserum.The recombination of immobilizing and agglutinating antibodies with lytic antibody revealed a reciprocal linear relationship, i.e., the lytic activity was more pronounced as the immobilizing titer decreased. The two antibody components when combined in a ratio of approximately 3:1 (immobilizing to lytic antibody), inhibited lysis and duplicated the immobilizing and gelatinous membrane formation observed for the unabsorbed cyst antisera.

Notes: SYNOPSIS. The effect of urethan on Poteriochromonas stipitata has been studied. Several concentration-dependent activities of the drug could be discerned. Low concentration increased cell yields; certain slightly higher ones resulted in complete cessation of growth. Further increase of urethan concentrations interfered with the respiration of the organism and still higher concentrations disrupted the cells.

Notes: SYNOPSIS. From an equation derived for measuring synchrony in microbial systems, a synchronization index (SI) may be computed, which depends on 3 parameters: (1) fraction of the population undergoing synchronous division; (2) time during which this synchrony of division occurs, and (3) generation time during normal exponential multiplication.Synchronization indices were computed and tabulated for 14 microbial cultures in which cell division was synchronized by different methods. The SI's range from 0.20 to 0.80. In the ideal situation—instantaneous doubling of the cell number in the mass culture—the SI is 1.00.

Notes: SYNOPSIS. Agar media have been used in plates, Burri tubes, and sealed slide preparations to grow trichomonads as clonal colonies. Periodic observation of slide-culture colonies confirmed their origin from single organisms as clones. Axenic cultures of Trichomonas vaginalis (3 strains), T. gallinae (2 strains), T. gallinarum (1 strain), Tritrichomonas augusta (5 strains), Trit. foetus (4 strains), Trit. suis (?) (6 strains), Pentatrichomonas hominis (1 strain), and an undescribed porcine form were used successfully. Urinary and vaginal specimens with T. vaginalis were also plated directly from patients. In all trials, organisms were recovered from colonies for broth culture and re-plating.Colonies of the two strains of T. gallinae showed constant differences in their growth under the same conditions. Plated T. vaginalis have shown zones of growth inhibition in tests against drug-impregnated discs.

Notes: SYNOPSIS. Streptomycin-bleached Euglena gracilis, strain Z, was cultivated under conditions which yielded good growth rates and high cell densities. Dividing cells produced only small amounts of carotenoid. After the cessation of cell division the carotenoid content of the cells increased rapidly. During the major period of carotenoid synthesis the cell number remained unchanged but the packed cell volume decreased. Some similar observations on carotenoid production by normal dark-grown Euglena are noted.

Notes: A variety of ciliates representing most of the major cliate groups were found to adhere to the ends of the tentacles of Podophrya collini. Reduction of ion concentration in the medium, low temperature, and treatment of the food ciliates or the suctorians with agents presumably interfering with choline-acetylcholine balances in the suctorian or ciliate depressed the capture efficiency. Addition of sulfhydryl containing com pounds to the feeding situation and treatments which reduced the swimming vigor of the ciliates gave enhanced capture efficiency. Although killed but unlysed ciliates would not adhere to the tentacle ends, agar particles containing ciliate breis or a mixture of salts plus experimentally determined organic compounds would adhere.

Notes: Schizocaryum dogieli Poljansky & Golikova, 1957, was discovered in four species of the echinoid genus Strongylo centrotus from San Juan Islands, Washington, during the summer of 1960. Specimens subjected to the Chatton-Lwoff silver impregnation technique have revealed that this species has been incorrectly assigned to the holotrich order Apostomatida. The presence of a vestibulum with sparse vestibular ciliature necessitates the transfer of this species to the holotrich order Trichostomatida as defined by Corliss. The infraciliature, certain pellicular organelles and the distinctive nuclear apparatus are described in detail. A discussion of various morphological and behavioral adaptations to its commensal mode of life is included. Detailed evidence is presented justifying the systematic reassignment of S. dogieli to the order Trichostomatida.

Notes: Oocysts of Eimeria acervulina Tyzzer, 1929 were collected at the time of their first massive discharge into the chick intestine, and isolated in the cold by means of continuous centrifugal flotation in high-density media. Maximum numbers (90%) of sporoblastic oocysts were obtained by incubating at 30°C for 10 hr and sporulation was considered complete within 20 hr. The initial Qo2 (dry-weight basis) of 9.5 decreased linearly to 〈 i/3 this value in 20 hr, and more slowly thereafter to very low levels. The QCO2 was higher than Qo2 only during the first 10 hr. A 15% decrease in dry weight in 15 hr was due chiefly to disappearance of alkali-stable carbohydrate, probably identical with glycogen. In the later stages carbohydrate was resynthesized. Lipids were not oxidized during sporoblast formation, but disappeared rapidly betweem 10 and 30 hr. Total nitrogen remained constant, indirect evidence suggesting that protein was not used to supply oxidative energy The change-over from carbohydrate to fat metabolism corresponded with observed changes in the respiratory quotient, and also with near-completion of sporulation. Apparently carbohydrate provided the energy needed for the earlier stages of sporulation, whereas oxidation of lipids supported the teal stages as well as the metabolism during dormancy.

Notes: The taxonomy of the so-called Sporozoa is reviewed, and it is concluded that the group is polyphyletic and should be split into the following independent taxa: (1) The subphylum EUSPORA subph. nov., members of which have simple spores without polar filaments; this subphylum contains the classes TELOSPORASIDA Schaudinn, 1900 and HAPLO-SPORASIDA Caullery and Mesnil, 1899; (2) the subphylum CNIDOSPORA Doflein, 1901, members of which have spores containing 1 or more polar filaments; (3) the class PIRO PLASMASIDA Wenyon, 1926, members of which have no spores, are parasitic in vertebrate erythrocytes and are heter-oxenous; and (4) the class TOXOPLASMASIDA Biocca, 1957 emend., members of which have no spores, have cysts or pseudocysts, and are monoxenous parasites of vertebrates; the latter two groups are not assigned to subphyla but are considered appendages to the Protozoa. A classification to suborders is given of the Euspora.

Notes: Electron and fluorescence microscopy reveal a proplastid about 1 μ in diameter in dark-grown Euglena gracilis quite like those in higher plants. After the cells are placed in the light these structures lengthen, probably in part by coalescence of several proplastids. Full size is reached in some cells after about one day in light. Lamellae, growing as blebs off the inner proplastid membrane, develop in a roughly linear fashion with time, art average of one new lamella appearing after each 6 hours in the light. The maturation of the proplastid thus appears to differ appreciably from that in higher plants since the latter presumably create several lamellae simultaneously, and these appear able to replicate themselves in a geometrically parallel fashion. The question is raised whether the apparent differences in development may not be due to lesser discrimination in observing the sequence in the higher plants, for there are no observations necessarily inconsistent with the sequence found in Euglena.

Notes: A number of isolates of the cellular slime mold, Acrasis rosea, differed from each other in the range of microorganisms on which they could grow and fruit. In a test for the possible occurrence of sexual reproduction and genetic recombination, two of the most widely divergent of these physiological races were studied further. Mixed colonies were obtained in agar plate cultures of Rhodotorula mucilaginosa, a yeast utilized by both. When spores from mature fruiting bodies or amoebae migrating out from the mixed colonies were isolated singly, regrown on Rhodotorula, and tested on a critical spectrum of food microorganisms, about 3-4% proved to be distinct from the original two strains. Although some of these new types remained stable for several transfers, they eventually reverted to one or both of the parental types. The possibilities of explaining the neotypes on the basis of diploidy, heterokaryosis, or mixed cytoplasmic effects are discussed. The occurrence of cell anastomoses and occasional binucleate cells favors the latter two possibilities.

Notes: Specimens of Glaucoma chattoni lacking in oral areas and unable to divide were observed in both axenic and bacterized cultures. The frequency of incidence of astomy rose in the course of continued cultivation of G. chattoni A, which was the strain most extensively studied.Observations on silver impregnated animals from mass cultures, and studies of individually isolated living ciliates, have both led to the conclusion that all cells destined to become astomous pass through a certain definite sequence of events. These axe: 1. Initial damage, not microscopically detectable, predisposes the cell in such a way that within a few generattons all of its progeny become astomous. 2. The ability to complete normal stomatogenesis is lost; the cell cannot maintain normal posterior oral anlagen and also cannot regenerate following damage to the existing oral area. At this stage the cell can still divide, so that astomous opisthes are produced. 3. The existing oral area disappears shortly after the ability to produce new oral areas is lost. Loss of ability to divide occurs simultaneously with loss of oral areas. 4. Finally, there is increasing disorganization of the kineties, gradually decreasing activity and death.The incidence of astomy was compared in several different strains of G. chattoni, including two newly isolated from nature.

Notes: Chilomastix equi n.sp., from the intestine of the Indian horse is described. The normal shape of the body is pyriform, posteriorly drawn out into a spike. The spiral groove is U-shaped and runs from one lateral side to the other. The nucleus is either ovoidal or spheroidal with an eccentric endo-some. Four blepharoplasts are present from which arise the anterior flagella, the cytostomal flagellum and the cytostomal fibrils. The arrangement of the four blepharoplasts differs markedly from the other known species, three being on the anterior border located in one row and the fourth adjacent to the nucleus. The three anterior flagella, arising from the first three anterior blepharoplasts, run backwards. The cytostomal flagellum arises from the fourth blepharoplast and rarely protrudes beyond the broad cytostome. The cytostome has a peculiar shape which distinguishes it from other species. The dimensions of the new species range (in microns) 15.7 to 31.5 in total length, 8.5 to 16.5 in body length proper, 6.0 to 15.5 in breadth and 4.0 to 17.0 in the length of the spike.

Notes: SYNOPSIS. In a cytochemical study of nuclear changes during encystment and excystment of Telotrochidium henneguyi, the micronucleus was not observed to undergo alterations to correspond with the cyst cycle. The macronucleus maintained its gross structural integrity but showed internal reorganization of its nucleic acids coinciding with encystment and excystment of the ciliate. Nucleoli forming in the macronucleus of early precyst trophozoites first appeared as Feulgen- or methyl greenpositive clumps. These increased in size, became homogeneous, accumulated nucleolar substances, and assumed a Feulgennegative or pyroninophilic character. As the nucleoli developed, the remaining macronuclear constituents imparted a variegated pattern to the macronucleus. After excystment the nucleoli disappeared and the variegated pattern in the macronucleus was lost. Nucleoli were lacking in the macronucleus of trophozoites taken from the logarithmic phase of the growth curve.

Notes: The occurrence of Babesiosoma stableri n. sp. in the erythrocytes of Rana pipiens pipiens extends the host range of babesiosomids to the Salientia. The proposed sequence of developmental stages includes the following events: (1) two successive nuclear divisions of the uninucleate trophozoite produce a tetranucleate organism, (2) cytoplasmic cleavage initiated at each pole of the tetranucleate parasite results in four daughter individuals arranged in a cross-form, (3) the four merozoites originating from the cruciform schizont separate without the formation of a residual mass of cytoplasm, (4) gametocytes which presumably arise from differentiated merozoites do not exhibit dimorphism. The morphology and characteristics of the parasite's development were not altered when B. stableri was experimentally transferred to: R. p. sphenocephala, Rana catesbeiana, Bufo americanus, Bufo woodhousei fowleri, and Bufo terrestris. Experimental infections, with few exceptions, exhibited a peak parasitemia followed by a decline in the number of babesiosomids. Infections persisted at a low level or disappeared during the period of study.

Notes: Dileptus anser is a relatively large multinucleate ciliate (gymnostome) which bears an anteriorly directed non-retractable proboscis. On the ventral surface of the proboscis is found a “feeding groove” which is bounded laterally by large feeding cilia. In the ventral mid-line of this groove is a small fiber which passes from the anterior tip to the cytostome-cytopharyngeal complex, which is located at the base of the proboscis. Electron micrographs show that this fiber is composed of smaller fibrils. These smaller fibrils are attached to the kinetosomes of the feeding cilia on both the right and left sides of the larger fibril bundle. Thus, the mid-ventral fibril bundle lies between two ciliary rows and provides fibrils for kinetosomes on both its right and left sides. Therefore, it seems likely in the case of this gymnostome, that there exists an exception to the rule of desmodexy as postulated by Chatton and Lwoff (1935). The function of these fibrils remains obscure but it is suggested that, in view of their close association with the feeding cilia and the non-retractable nature of the proboscis, their function may be primarily coordinative. However, the possibility that they may also be concerned secondarily with minor contractions is not excluded.The armature of the cytostome-cytopharyngeal complex is composed of two distinct systems: (1) a system of fibrils which are apparently kinetodesmal and (2) a system of trichites. The fibrils are thought to be associated with the feeding cilia of the proboscis as well as with those which surround the cytostome. The fibrils extend into the cytoplasm of the armature and are intermingled among the trichites. The tri-chites are arranged in two concentric cones around the cytostome. In the outermost cone they are larger and arranged in almost single file as opposed to the smaller size and the more or less random orientation of those of the inner cone. They are composed of smaller hexagonally packed rods which measure 170-180 Å in diameter and are separated by a space of about 100 Å.

Notes: Of fragments involving a partial removal of the original adoral zone of membranelles (AZM), the monomacro-nucleate ones become reorganized monostomes resulting from a simple fusion of the remnant AZM to the oral primordium induced, and the binucleate ones become dividers by initiation of the oral primordium posteriorly from the posterior terminal of the remnant AZM. The cirral primordium in any fragment arises alongside its corresponding oral area. Weisz's idea of the dominance and inhibition of the original oral system extending over the oral primordium site is applicable in stomatogenesis of the present species. This application is found also in cirral formation.In fragments from early stage dividers, a formed oral primordium is easily absorbed by influence of the intact original AZM. This event also occurs after complete removal of the AZM. Such results led to the hypothesis that the oral primordium in the normal divider may be formed under some stoma-togenic activation of the AZM followed by escape from inhibition also arising from the same source. Irrevocable furrow formation and irreversibility of the oral primordium in stomatogenesis occur in later stages of division. Nevertheless division in these stages is blocked when certain operations are performed, forming monsters possessing the AZM of the opisthe translocated to the side opposite to that of the proter. In other monsters obtained from a fusion of the AZM of the proter to that of the opisthe, division occurs belatedly, prior to which secondary oral and cirral primordia are produced.

Notes: A new astomatous holotrichous ciliate, Radiophryoides puytoraci, parasitic in the gut of the Indian freshwater oligochaete is described. This is the second finding of the astomatous ciliate parasite from the microdrili from Asia. Key to all the known and valid species of Radiophryoides is given.

Notes: The in vivo absorption spectra of the chloroplast and eyespot of Euglena gracilis were obtained by microspectro-photometry. The average chloroplast absorption spectrum shows major peaks at 430-43S and 675-685 mμ. The fine structure details of chlorophyll à show peaks at 675, 685 and 695 mμ. The average eyespot absorption spectrum shows major absorption in the region of 460-490 mμ, and two additional peaks near 510 and around 530 mμ with lesser peaks at 430 and 630 mμ. Some of these same absorption peaks were obtained for the eyespot of E. granulata and the “hematochrome flecks.” The eyespot spectrum indicates that probably more than one ca-rotenoid is present and that a correlation exists between the eyespot absorption spectrum and the Euglena phototactic action spectra.

Notes: SYNOPSIS. The mechanism of carbohydrate dissimilation was studied in cell-free extracts prepared from mass cultures of the trichomonads. Evidence for the presence of all the enzymes associated with the Embden-Meyerhof glycolytic scheme was obtained. Several enzyme systems directly associated with the glycolytic pathway were examined. Two of these, alcohol dehydrogenase and phosphorylase, were not demonstrated in the T. vaginalis extract. The absence of phosphorylase in the presence of a very high glycogen concentration in the cell (20.8%) suggests the possibility of an alternate route. A very active TPN-linked “malic enzyme” was also demonstrated, although no functional citric acid cycle is known for this trichomonad. Based on the experimental evidence and collateral data, a functional Embden-Meyerhof system was suggested for T. vaginalis.

Notes: SYNOPSIS. A technique for the axenic cultivation of Trichomonas tenax, the oral flagellate of man, is presented. The medium employed consists of a nutrient broth supplemented with horse serum and a cell-free extract of chick embryo. Three strains established in this medium have been maintained for 16, 23 and 48 months respectively.All the cultures were initiated with trichomonads grown in association with Trypanosoma cruzi. Attempts to establish axenic cultures with trichomonads obtained from xenic cultures containing a bacterial flora of unknown composition met with failure. This suggests that the successful cutcome of the process of axenization is to a certain extent dependent upon the type of organism(s) with which T. tenax is associated in culture. Furthermore, these findings may serve to explain earlier failures since not only were all of these attempts made with media lacking tissue extract supplements but all were made using bacteria-trichomonad cultures as a source of trichomonads.

Notes: SYNOPSIS. Several trichomonads from poikilotherms (Hypotrichomonas acosta, Monocercomonas colubrorum and M. sp., Trichomonas batrachorum, and Tritrichomonas augusta) grew in a nearly-defined medium to a level of 10–40% that permitted with media containing casein digests; T. augusta (4 strains) grew best. The defined medium contained TEM-4T (a semisynthetic fat based on beef-tallow fatty acids) and ascorbyl “palmitate” as sources of fatty acids. Besides ascorbyl palmitate, thiomalic and ascorbic acids, and tocopherol served as reducers and antiöxidants. High concentrations of nucleotides (adenylic, cytidylic, guanylic, and uridylic acids) seemed necessary. Indigo carmine was a useful redox indicator; the flagellates never grew in the oxidized zone. Extra trace elements and amino acids or rich natural media permitted better growth at about 34.5°C—the upper temperature limit for these trichomonads, raising the issue of a biochemical basis of a thermal barrier to the invasion of warmblooded hosts. Except for the limited carbohydrate in the nucleotides, carbohydrate could be omitted, the main substrates being a combination of glycerol, acetate, and gylcero-phosphate, posing the question of the identity of the anaerobic, presumably non-glycolytic, energy-yielding pathway.

Notes: SYNOPSIS. Nitrogen mustard (HN-2) in vitro decreased virulence of T. equiperdum, without influencing motility or morphological characteristics. Pretreatment of mice with tolerated doses of HN-2 (2.5–5.0 mg/kg) delayed and decreased parasitemia. Sensitivity of the trypanosomes to tartar emetic (TE) was insignificantly modified, if at all, by in vitro exposure to HN-2. Trypanosomes exposed in vivo to HN-2 during 25 or more mouse passages showed a decreased sensitivity to TE and to aromatic arsonic acids. The decreased TE sensitivity appeared generally in the form of early relapses, though in a number of cases doses as high as 15 mg/kg had no clearing action. After discontinuance of HN-2 treatment, the strains reverted after a variable number of animal passages to their original sensitivity even under TE treatment. This reversion to original sensitivity is not related to relapse phenomena, since it occurred also after passage from animals which were not influenced at all by TE treatment. T. equiperdum strains exposed in vivo to HN-2 produced antisera in mice which did not agglutinate the original trypanosomes, whereas antisera against the original trypanosomes agglutinated all HN-2 treated strains. The pronounced decrease of sensitivity to arsonic acids obtained by HN-2 treatment had a stable character, in contrast to the TE resistance which was transient and of low magnitude.

Notes: SYNOPSIS. Dividing forms of Trypanosoma simiae and T. congolense in stained thin blood films taken from pigs infected by wild Glossina morsitans submorsitans were measured employing a technique which took account of the distance between the divided kinetoplasts, the positions of the nucleus or nuclei and the lengths of the original and developing flagella.Analysis of these measurements showed that binary fission in these trypanosomes consisted of a gradual increase in the distance between the divided kinetoplasts along the long axis of the body; progressive outgrowth of a daughter flagellum from the blepharoplast associated with the posteriorly placed kinetoplast; migration of the nucleus toward the posterior end of the body; separation of the divided nuclei in the direction of the long axis of the body; and fission of the cytoplasm in an antero-posterior direction and finally separation into two individuals by a stepped, sliding motion.No evidence to support syngamy or other type of germ cell reproduction was observed.

Notes: SYNOPSIS. The “Laredo strain” of Entamoeba histolytica has been reported to have different temperature requirements for growth than the usually known strains of the species, although morphological and antigenic tests have thus far indicated no significant recognizable differences. Further genetic studies show the Laredo strain to exhibit at least four characteristics different from the usual. Also, a freshly isolated strain (BA) was shown to have the same characteristics as those previously reported for some well-known strains.

Notes: SYNOPSIS. Of 17 derivatives of 3- and 5-nitropyridine and pyrimidine which inhibited Trichomonas vaginalis in vitro, 7 also inhibited in vivo. The ones with the greatest in vitro activity, and the only ones that were active in vivo, were 5-nitropyridines and pyrimidines with a single substituent at C2. With combinations of compounds, the in vitro inhibitory action was additive. The in vitro inhibitory activity of each was reversed by structurally related compounds, e.g. 2-acetamido-5-nitropyridine. All inhibitors presumably were acting similarly. In later work with 2-amino-5-nitropyrimidine (inhibitor) as model compound, the inhibition represented by extreme prolongation of the generation time was immediately reversible on removal of the inhibitor and without subsequent effect on the lag phase or generation time of the surviving cells even in a population made up of 〉90% non-viable cells.Staining indicated that, after 2-hour growth with inhibitor, mitosis was arrested at prophase. To verify this subjective observation, cells were exposed to both inhibitor and 10−3 M colchicine since after 5-hour growth with colchicine all cells were in “c” (colchicine)-mitosis. If the inhibitor did act at prophase, then cells exposed both to inhibitor and colchicine should proceed only as far as prophase. This proved the case.Since 2-amino-5-nitropyrimidine had the same killing characteristics as 2,4-dinitrophenol (DNP), which blocks mitosis at prophase by inhibiting phosphorylation, the metabolism of resting cells was compared in the presence of 4 × 10−4 M DNP (the concentration 90% growth inhibitory) or 2-amino-5-nitropyrimidine. This concentration of DNP uncoupled phosphorylation since it stimulated the rate of reduction of 2,3,5-triphenyltetrazolium chloride. 2-Amino-5-nitropyrimidine did not change the metabolic rate on simple addition to resting cells. But when cells were grown with at least 40μg/ml for at least 3 hr, endogenous metabolism was inhibited while utilization of malate was stimulated and became linear with time. It was demonstrated that both metabolic disturbances were due to accumulation of diphosphopyridine nucleotide (DPN). Accumulation of DPN was not responsible for prophase blockage. The lesion resulting in prophase blockage remains unknown.

Notes: SYNOPSIS. Three hr after a leech feeds on infected fish the blood trypanosomes appear in the crop. There they first decrease in size, the kinetoplast moving forward, the undulating membrane and free flagellum being shortened. After one day stumpy forms and others in which the kinetoplast is approaching the nucleus, as well as some dividing forms, appear. Two days later they become numerous and assume the crithidial form. In this stage they multiply till the 6th day, when they are transformed into attenuated trypaniform flagellates. After 7 days multiplication stops and they become typical slender trypanosomes representing infective metacyclic forms. By the 10th day these migrate from the crop into the proboscis sheath and are transmitted by the inoculative method when the leech feeds on a new host.

Notes: SYNOPSIS. Euplotes minuta Yocom, 1930, which has not been reported since its original description, was isolated in 1961 from a tide pool on the New Hampshire coast. Specimens from cultures derived from a single individual averaged 54μ long and 28μ wide. The buccal cavity has an average length of 41μ and contains 31–40 membranelles. There are ten fronto-ventral cirri, five anal cirri, four caudal cirri, and nine dorsal bristle rows. E. minuta is compared with similar species in the genus and found to be a valid species on the basis of presently accepted criteria.

Notes: SYNOPSIS. Respiration of Tetrahymena pyriformis W, grown in Proteose peptone-glucose medium, was determined by Warburg's direct and indirect methods. The Qo2 varied inversely with cell concentration under exogenous conditions (cells in conditioned medium, i.e., one which had supported growth) as determined by both methods, and under endogenous conditions (washed cells suspended in salts solution) when determined by the indirect method. Endogenous respiration, measured by the direct method, was low but independent of cell concentration.Respiration, determined by the direct method, was little affected by lowered O2 availability, but varied directly with nutrient availability. The inhibitor, malonate, which also stimulates respiration at greater dilutions, inhibited respiration at 10−2M when present with low cell concentrations, but stimulated at high cell concentrations.The reduced respiration at higher cell concentrations is thought less due to lack of O2 than to CO2 accumulation and competition for nutrients. Consideration of these variables is essential in comparing data from the literature.

Notes: SYNOPSIS. Cultures of Trypanosoma ranarum at room temperature, 20° or 25°C had similar patterns of growth and cyclic development, i.e., change from pear-shaped to slender forms. At 9° the cycle of development and reproduction was compressed, but returned to normal after introduction to optimum temperatures. A compressed cyclic and reproduction rate was noted at 31° but return to optimum temperature did not reestablish normal cultural development. At 35° all flagellates were killed after 24 hr. The relation between reproductive capacity, cyclic development, and temperature is discussed speculatively.

Notes: SYNOPSIS. A procedure is described which allows quantitative evaluation of the rate of dye uptake by phagotrophic activity of Tetrahymena. A fixation solution which retains integrity of vacuolar membranes for at least 7 hr, and of the pellicular membrane for about 3 hr, is also described.

Notes: SYNOPSIS. Tritiated thymidine and autoradiographic methods were used to investigate the cyclic DNA synthesis in the culture form of Trypanosoma mega. It was found that the mean generation time of 18.9 hours comprises four successive periods: G1, S, G2 and D. The interphase lasts through the first three. S is the phase of DNA synthesis of both the nucleus and the kinetonucleus (kinetoplast). The cell divides during D, beginning with the division of the kinetonucleus. The respective durations of G1, S, G2 and D are 8.5, 7, 2 and 1.4 hours. The close time relationship between the two DNA synthesizing bodies is considered as bringing support to the old theory of the Binucleates and the possible genetic function of the kinetonucleus is suggested.

Notes: SYNOPSIS. In chemically defined media at carbohydrate concentrations ≧ 0.5% (w/v) Tetrahymena pyriformis W multiplied more rapidly, developed larger cells, and achieved greater growth as measured by optical density when carbohydrate was provided as dextrin rather than glucose. In media containing 0.3 mg/ml of amino acid nitrogen, growth increased with glucose concentration from 0.1 to 1%, did not change significantly to 3%, and was sharply inhibited at higher glucose levels. With dextrin, maximum growth paralleled carbohydrate concentration from 0.1 to 3%. At higher N levels the inhibitory concentration of glucose was lowered, but growth in dextrin media was not affected except at N concentrations that were inhibitory independent of carbohydrate source. At 1% carbohydrate levels, total cell protein per ml of culture was 60% greater, protein per cell approximately 50% greater, and cells were 1.5 to 2 times larger in media with dextrin than with glucose. Comparable differences in protein synthesis were observed at 2% carbohydrate levels and efficiency of conversion of substrate-N to protein-N was greater in the medium with dextrin than glucose.Growth as measured by optical density in media with 0.3 mg/ml of N and 1 or 2% (w/v) of dextrin was not significantly reduced by the simultaneous presence of 1 or 2% glucose. This observation appeared to negate osmotic pressure as an explanation of reduced growth in the presence of glucose. At higher osmolar concentrations osmotic pressure appeared to be a major determinant of overall growth but not of cell size.

Notes: SYNOPSIS. Octogenic reproductive cysts are transformed into resting cysts when returned to optimal temperature following prior exposure to cold (5°C) for at least 36 hours. In the cold, the reproductive process ceases and macronuclei revert to the interphase condition. Transformation to resting cysts is synchronous. Induced encystment is accompanied by excessive macronuclear extrusion and is associated with a loss in division potential, resulting in no division, or 1 or 2 divisions in the induced resting cyst.These observations support the hypothesis that exposure to cold during a critical period of the predivisional stage may alter reproductive protein synthesis and favor cyst protein synthesis. The extensive macronuclear extrusions associated with this transition suggest their biochemical involvement in the encystment process.

Notes: SYNOPSIS. Toxoplasma aggregates in sub-acutely and chronically infected mouse brain were studied with special regard to interparasitic relationships, encapsulating wall formation and host-parasite interaction. The individual parasites within a cyst are separated from one another by an opaque substance which also appears as a component of the cyst wall. A second constituent in the wall consists of vesicular and membranous structures which presumably are derived from the endoplasmic reticulum of the host cell. In small cysts, the organising are loosely arranged and maintain the typical crescentic shape whereas, in large cysts, they are tightly packed and polygonal in outline. It is concluded from the data obtained that only the term “cyst” correctly designates these parasitic aggregates.

Notes: The incidence of Hepatozoon balfouri (Laveran, 1905) in examined populations of Egyptian jerboas was 41% in Jaculus j. jaculus, 21% in Jaculus o. orientalis, and nil in Allactaga tetradactyla. Infection in a few animals apparently less than 6 days old suggests the possibility of transplacental transmission. The cycle in erythrocytes and parenchyma cells of the liver is described; stages in liver are seldom seen in chronic infections. Blood of many other Egyptian rodents and insectivores was negative for H. balfouri.The sporogonic cycle in mites, Haemolaelaps aegyptius Keegan, 1956, fed on infected jerboas, resembles that of other typical Hepatozoon species. Sporocysts contain 6 to 16 (usually 12) sporozoites. Infection rates in experimental cultures of H. aegyptius varied greatly. Mites from only a single graphic area could be experimentally infected; in the same area, the infection rate in J. jaculus is significantly higher than elsewhere. Biological races of Haemolaelaps aegyptius, more or less refractive to H. balfouri infection, may exist. Large numbers of mites, lice, fleas, and ticks removed from infected jerboas were uninfected, as were numerous arthropods experimentally fed on infected jerboas.Owing to the presence of H. balfouri foci in widely differing ecological zones of North Africa and Sudan, different species of mites, and possibly of other arthropods, obviously transmit the infection; details of this likelihood require further investigation.

Notes: SYNOPSIS. Ochromonas danica and O. malhamensis were grown in the presence of Na2S35O4. Four chloroform-soluble S35-compounds were separated from them, one of which was also found in the chloroform extract of Chlorella pyrenoidosa. All four S35-compounds were hydrolyzed by acid to yield S35-sulfate. Two of the S35-compounds were fed to O. danica and incorporated into the organism without reduction of the S35-sulfate. Evidence is presented suggesting a structural relationship between these chloroform-soluble S35-compounds.

Notes: SYNOPSIS. The life cycle of the zooxanthella of Cassiopeia sp., as determined by in vitro studies, includes a dominant vegetative autotrophic stage, a reproductive cyst producing autospores, aplanospores, or motile gymnodinioid zoospores, or possible gametes. The predominance of these stages is partially determined by environmental factors, e.g., photoperiodicity. As none of the existing genera of free-living or parasitic algae are wholly applicable to this organism, a new genus, Symbiodinium, is proposed. The type species, S. microadriaticum, is described.

Notes: SYNOPSIS. Most tricarboxylic acid cycle intermediates are oxidized by intact cells of the apochlorotic flagellate Astasia longa (Jahn). Use of these substrates depends on the pH of the medium. The acetate-stimulated respiration is much more sensitive to metabolic inhibitors than is cell motility. The following glyoxylate cycle and/or tricarboxylic acid cycle enzymes have been demonstrated in cell-free extracts: acetic-thiokinase, condensing-enzyme, aconitase, TPN-isocitric dehydrogenase, succinic dehydrogenase, fumarase, and malic dehydrogenase.

Notes: SYXOPSIS. The duration of photic suppression of plasmosol movement was used as a measure of the sensitivity of Amoeba proteus to selected wavelengths of monochromatic stimulation. Radiant energy was equated across the wavelengths which ranged from 420 to 620 millimicrons. The data generally confirm previous findings but indicate that maximum sensitivity lies in the green (515 mμ) rather than the previously held blue (450-490 mμ) region.

Notes: Frontonia microstoma, a ciliate living in brackish water, is described. The somatic infraciliature, the buccal in-fraciliature and the fibrillar buccal system show essential characteristics of species of Frontoniidae Kahl. The number and the arrangement of vestibular kineties are specific. Dark blue-green pigment is formed by small ectoplasmic vesicles. Formation of cysts is frequent in natural medium and cultures. There is no dedifferentiation of ciliates when encysted. Excystment is induced readily. Thriving cultures of F. microstoma have been obtained by feeding the ciliates with appropriate species of Cyanophyceae. Growth was better in brackish water than in either sea water or fresh water.

Notes: An amicronucleate clone of Tetrahymena pyrijormis has been found among the asexual progeny of irradiated cells of strain EU 6000 (variety 6, mating type I). Log-phase cells of this clone, designated EU 6525, have a mean generation time (6.0 hr) longer than that of the micronucleate strain, EU 6000 (2.9 hr). Further irradiation studies of strain EU 6000 indicate that the recovery of viable amicronucleate populations is rare although many amicronucleate cells are found among surviving progeny.1 Attempts to introduce micronuclei into amicronucleate cells of strain EU 6525 by conjugation have been made. Micronucleate lines are obtained from amicronu create pair members only in low frequency. These results, considered together with those of other workers, suggest that some change in the state of the cell, additional to the physical loss (or gain) of the micronucleus, must occur before viable amicronucleate clones can be obtained from micronucleate cells, or before amicronucleate cells can produce viable micronucleate lineages. An alteration in mean generation time may be a reflection of this change, or it may simply be a direct consequence of micronuclear removal. The results further imply that the ciliate micronucleus unquestionably contributes information to the cell during asexual growth and reproduction.

Notes: The chromosome cycle in the vegetative division of Euglena viridis was investigated. The seeming chromatin granules in the interphase nucleus are in reality thread structures, paired and very loosely twisted. Each component of the paired threads is called a chromatid, and consists of a fine thread of even thickness, the chromonema.In the prophase, linear contraction and thickening of the chromatids occurs by means of the spiralization of them. In the later prophase, the coiled chromonema splits into two finer strands which show the plectonemic spiral. At the metaphase, the chromosomes are arranged in the form of an equatorial ring, encircling the median portion of the elongated endosome. Nearly all of the chromosomes have a submedian or a sub-terminal and a few of them have a terminal kinetochore. In the early anaphase, separation of the sister chromosomes takes place beginning at the kinetochore. The spindle fibres in the metaphase and anaphase were not observed. The two stranded spiral in the chromosomes is separated into distinct components by the uncoiling in the later telophase, and they are transformed, in the interphase nucleus, into the paired chromatids.

Notes: Six strains of Entamoeba histolytica were studied in an initial attempt to define some genetic characteristics. Sugar metabolism and drug sensitivity were the markers studied. The six strains showed little difference in characteristics and attempts to obtain mutations have been unsuccessful. The observed characeristics may be useful in helping to define the species.

Notes: Oxidative assimilation of acetate by Euglena gracilis was studied using methyl- and carboxyl-labeled radioactive acetate. Of the total carbon utilized, 40% was oxidized to CO2 and 60% was assimilated; 20% of the CO2 produced was derived from the methyl carbon, and 80% from the car-boxyl carbon of acetate. Seventy % of the carbon assimilated was derived from the methyl carbon and 30% from the carboxyl. The results suggest that assimilation involves decarboxylation of Krebs-cycle oxalacetate and assimilation of the resulting pyruvate.In the presence of ethanol a greater proportion of the acetate carbon is assimilated, though the total acetate consumption is almost unchanged.

Notes: Induction of conjugation in clones of variety 7 of Tetrahymena pyriformis required more precise control than was necessary for the classical variety 1 clones, WH-6 and WH-14. Axenic methods are herein described which were successful in eliciting the mating response; especially important was a period of growth under optimal nutritional conditions, and use of animals in the logarithmic phase of growth.Three cases of presumptive age-induced selfing are reported, along with the discovery of new mating types III and IV. The isolation of a stage intermediate between a “pure” marine type and a selfing condition offers additional evidence for mating type instability. An analysis of the system of mating-type inheritance shows a pattern similar to that seen in Paramecium aurelia (Group B), and variety 9 of Tetrahymena pyriformis.

Notes: Ingestion of fluid by axenically cultured Tetra-hymena pyriformis requires an inducer, which can be provided by peptone-yeast extract broth. Cells in this medium contain many phagotrophic vacuoles; the formation of these is readily followed by allowing peptone-yeast grown cells to ingest the impermeable dye, trypan blue. Tetrahymena grown in synthetic medium contain only few vacuoles and do not ingest trypan blue to any significant degree. Addition of peptone-yeast medium to cells grown in a synthetic medium “induces” vacuolar formation and uptake of the dye. Calculations based on the rate of ingestion of trypan blue and of heat killed cells of Serratia marcescens indicate that the phagotrophic process cannot adequately supply the nutritional demands of the organism. Experiments using the colored amino acid analog, 3,5-dinitrotyrosine contrast the rapid penetration of material through the cell membrane with the more sluggish route of phagotrophy.

Notes: Histomonas meleagridis was successfully cultured without demonstrable bacteria in a modified tissue culture medium enriched by fresh hamster liver and metal ions.

Notes: The morphology and division of Entodinium dubardi dubardi Buisson 1923, found by the present writer in the rumen of a white-tailed deer (Odocoileus virginianus borealis) from the state of New York, are described. E. longi-nucleatum was found for the first time in this host. A transitional form of E. d. dubardi leading to E. d. cervi Sladecek 1946, was seen. Rotund or orbicular-like individuals occurring in the material are the postdivisional stages of E. d. dubardi. Comparative study of preparations from the mule-deer Odocoileus hemionis hemionis, O. hemionus Macrotis, and another white-tailed deer gave the same results as in the study of the principal host. Very close resemblance of the post-divisional stages of E. d. dubardi with E. bovis Wertheim and E. orbicularis Bush & Kofoid is noted. New data have been established to regard E. simplex Dogiel as a synonym of E. d. dubardi.

Notes: Disematostoma colpidioides von Gelei, 1954, is a Peniculina which stands out principally by a very markedly-twisted shape, resulting from the allometric growth of some of the right somatic kineties, and by the sigmoid curvature of the postoral suture. During the fission of the macronucleus, it is possible to observe the expulsion of a small chromatic mass which degenerates quickly. A part of the buccal apparatus undergoes a dedifferentiation during the encystment, so that the three “peniculi” disappear while the vestibulary kineties persist.

Notes: Most of the thigmotrichous ciliates of the family Ancistrocomidae are parasites of gastropod and pelecypod mollusks. The only known exceptions are Hypocomella pho-ronopsidis, from a phoronid, and some species of Hypocomella and Heterocinetopsis which parasitize the oligochaete Chaeto-gaster limnaei as well as certain of the fresh-water snails with which this worm is commensal. Two new species of marine ancistrocomids, found on the Pacific coast of Oregon, infect hosts belonging to groups from which ciliates of this type have not previously been reported. Hypocomella katharinae sp. Now is a parasite of the ctenidial epithelium of the chiton Katharina tunicata. Ignotocoma sabellarum gen. nov., sp. nov., is found on the peristomial cirri of two polychaete annelids of the family Sabellidae: Schizobranchia insignis and Eudistylia polymorpha. The genus Ignotocoma differs from previously described genera of ancistrocomids in having its ciliary system separated into two fields, each consisting of seven or eight rows, which are largely limited to weakly concave areas lying on opposite sides of a longitudinal ridge-like eminence on the inferior surface.

Notes: Bleaching (interference with chlorophyll accumulation) by streptomycin (SM) is more effective when dark-grown Euglena gracilis cells are exposed to SM in the dark for several days than when exposure of dark- or light-grown cells is exclusively in light. Cells are also bleached when exposed to SM while lacking both chlorophyll and chloroplasts (i.e., exposed to SM in the dark and subcultured to SM-free medium before transfer to light). Bleaching therefore involves inhibition of the formation of a plastid or pigment precursor, rather than breakdown of chlorophyll or interference with replication of mature chloroplasts. Bleaching by SM B prevented by addition to the medium of any of several fin cations, including Mg. Therefore it is proposed that bleaching results from chelation of Mg by SM. thus blocking a Mg-requiring step in chlorophyll synthesis. Disruption by SM of chloroplast structure and/or development is considered a secondary consequence of the bleaching action, resulting from the essentiality of intact chlorophyll molecules for normal chloroplast structure.