ALBERT

Notes: SYNOPSIS. Ten new species of colorless Eugleninae are described. One of them is the type of a new genus (Calycimonas physaloides nov. gen. nov. sp.). Especially remarkable forms are: Astasia acus, a species related to the green Euglena acus but without chromatophores and stigma and considerably smaller; Astasia edax, a species with animal-like nutrition and peculiar ecological adaptations; Petalomonas striata, a form which is not spirally but transversely striated; and finally Hyalophacus caecus, which was observed already by Klebs and Pochmann but was not sufficiently described. The new genus Calycimonas (ex fam. Peranemacearum) is related to Tropidoscyphus on the one hand (nearly the same shape as e.g. Tr. octocostatus, but possessing only a single flagellum) and to Petalomonas on the other hand (mode of nutrition and of swimming, formation of the reservoir, rigidity: however in transverse section not flattened).The Astasiae with zootrophic nutrition are collected in a new subgenus Astasiae devorantes or Phytophaga which comprises besides A. edax three species already described by Skuja.

Notes: SYNOPSIS. H. canis (James) is reported from three of 36 stray dogs at Singapore and one of 34 palm civets (Paradoxurus hermaphroditus Pallas) from Jeram, Selangor. H. muris (Balfour) was found at Singapore in 10 of 61 examples of Rattus norvegicus (Erxleben) and five of 23 of R. rattus diardi (Jentinck), and is also recorded from six of 139 examples of R. r. jarak (Bonhote) from Pulau Jarak, Straits of Malacca. Neutrophils of P. hermaphroditus containing gametocytes of H. canis exhibit pronounced karyorrhexis, while most of the parasites themselves show signs of pyknosis.

Notes: SYNOPSIS. A total of 155 clones of Stylonychia putrina collected in nature were tested for mating type. Two sexually isolated varieties were found among them: Variety I with 12 mating types and Var. II with 11. Five of the clones isolated in the laboratory belonged to 3 additional mating types of Var. I making a total of 15 mating types in this variety.Crosses were made among 6 of the mating types of Var. I, and 114 clones of progeny were raised and tested for mating type. No simple genetic explanation of the results was evident.An abnormal type of conjugation with fusion of the conjugants and subsequent fission was studied. Both parental mating types sometimes segregated during the first two fissions of a fused animal. Mating type determination in the progeny of the fused animals seemed to parallel that of the progeny of the normal conjugants in that in both cases certain mating types tended to be dominant over others.

Notes: SYNOPSIS. The cytochemical procedure of Sen was used to demonstrate urease activity in Tetrahymena pyriformis S.

Notes: SYNOPSIS. The chimpanzee is shown to behave like man to infection with Babesia divergens or bovis: the intact animal is totally resistant, whereas the splenectomized animal develops a fulminating infection accompanied by blackwater. The splenectomized rhesus monkey reacts in the same way also, but splenectomized rabbits are insusceptible. In the chimpanzee the typical accolé position of the “divergens” organisms (as seen in cattle) is absent, but occurs in the rhesus. It is suggested that latent piroplasmosis in man may exist on a large scale in rural populations in infected localities.

Notes: SYNOPSIS. Studies cf 3 conjugating strains of Tetrahymena pyriformis grown in a bacterized medium indicated the presence of a system of alternative immobilizing surface antigens. Each strain was found to have the potential for the expression of 3 serologically unrelated antigens. These consisted of a “high temperature” antigen (expressed in the range of 20–35d̀C), a “low temperature” antigen (exhibited in cultures at 10d̀), and an antigen induced by growth in the presence of the above-mentioned “high temperature” antiserum. Normally, by the immobilization reaction, only one of these antigens could be detected as present on any one organism at any given time. The “high temperature” antigens of two of the strains were serclogically related while that of the 3rd strain did not cross-react with antisera to the other two. The “low temperature” antigens of the 3 strains were serologically related as were the antigens induced by growth in antiserum.Studies of inbred hybrids of two of the strains indicated a potential for still more alternative antigens as well as for the spontaneous expression of the antigen which in the parental strains could only be induced to appear by the presence of the specific antiserum.Study of the 3 strains in axenic medium indicated the existence of a more complex system and the possibility that two or more immobilizing antigens may be present simultaneously.

Notes: SYNOPSIS. The establishment of Eimeria tenella sporozoites in the cecal mucosa of the chicken is described. The invasion process was similar to that reported for E. necatrix by Van Doorninck and Becker. Sporozoites were found to pass through the surface epithelium of the cecal mucosa into the lamina propria. Within the lamina propria the sporozoites were engulfed by macrophages and transported to the cells of the glands of Lieberkühn. Development of the sporozoites ensues within the gland epithelium.

Notes: SYNOPSIS. The morphology of the vegetative phase and the sexual process in Pandorina morum have been studied in detail under controlled laboratory conditions. A number of strains from various areas of the United States, all essentially indistinguishable on morphological grounds, were analyzed for sexual compatibility. Forty-seven heterothallic clones were found to represent 15 separate pairs of mating types, or a minimum of 15 syngens (sensu Sonneborn, 1957). Two clones proved to be homothallic. Nine additional clones, which were not observed to mate with any strain, can be classified only after further collecting. The separate heterothallic pairs of mating types are sexually isolated by factors acting at the stage of gamete production; incompatible mating types produce no gametes when they are mixed together. The geographical distribution of the sets of mating types is very incompletely defined as yet, but they are not strictly endemic forms. Thirty heterothallic strains, representing each of the 15 sexually isolated sets of mating types of Pandorina morum, have been deposited with the Culture Collection of Algae maintained at Indiana University, Bloomington, Indiana, U.S.A.

Notes: SYNOPSIS. When grown in CPLM medium or in a similar medium containing glucose instead of maltose as its sugar, Tritrichomonas foetus, Strain O, was much more sensitive to injury when frozen to -21d̀ C. in the presence. of 1 m glycerol during the initial and logarithmic phases of its population growth curve than at its peak and for some time thereafter. In 7 experiments in which the population peak occurred an average of 28.1 hours after inoculation, the average culture age at which the protozoa first survived freezing was 20.3 hours, at which time the population had reached 52.6% of its peak. The optimum culture age for survival after 1 day of freezing averaged 37.7 hours at which time the population averaged 75.6% of its peak. The optimum culture age for survival after 7 to 15 days of freezing averaged 32.3 hours, at which time the population averaged 82.7% of its peak. Better survival upon freezing was obtained in those experiments in which the population peak was reached relatively rapidly.

Notes: SYNOPSIS. Specimens of Blepharisma undulans were transferred from young clone cultures to a rotocompressor with 3 mm3 of culture medium. The organisms were slightly compressed and photographed at various intervals with dark field illumination. The sequence of macronuclear and cytoplasmic changes was compared with similarly followed Feulgen preparations.The cycle falls into several phases: (1) an interphase (12–24 hr.) in which the organism increases in size while cytoplasmic and macronuclear appearances remain unchanged. During this phase, the macronucleus consists of 3 to 5 nodes of various sizes connected by strands. (2) a pre-condensation phase (1 hr.) in which a new posterior peristome and cytopyge appear without visible macronuclear change. (3) a condensation phase (10–20 min.) in which the macronuclear nodes coalesce into a round mass without dissolution of the central nodes or strands. (4) a postcondensation phase (1 hr.) characterized by: (a) elongation of the condensed macronucleus into a rod-like shape followed by typical nodal formation; or (b) elongation of the condensed macronucleus into a form resembling the letter “J”, followed by nodal formation, and resulting in a double row of nodes in one daughter and a single row in the other. Separation occurs at this time, initiating the new interphase. The development of the j-form macronucleus. the lack of obliteration of the central nodes, and the characteristic interphase condition distinguish this strain of B. undulans from others described elsewhere.

Notes: SYNOPSIS. Six species of astomatous Infusoria, 4 new, are described from the alimentary tract of Oligochaeta from Ochrida Lake. Two belong to Ochridanus, characterized by a cytoskeleton whose “V”-shaped basal piece bears on its branches two articulated hooks brought together by a skeletal blade. This genus found in Ochridanous Tubificidae represents the counterpart of Anthonyella in the Lumbriculidae of Lake Baïkal. The presence of Ochridanus in these worms concurs with the almost complete absence of representatives of Radiophrya of which we have found but one species. A species of Metaradiophrya, a genus unknown to date from the Lumbricidae, was noticed in Glossoscolecidae. The different species of Ochridanus, Anthonyella, Metaradiophrya, and Radiophrya compose a very homogeneous group of Radiophryinae. The study of the ciliary rows and the cytoskeleton of 2 species of Juxtaradiophrya, parasitic in the Lumbriculidae of Ochrida, shows that, in the morphology of these ciliates, as well as in the same forms from Lake Baïkal, many transition characteristics exist between the Radiophryinae and Hoplitophryinae or Mesnilellinae. These 3 sub-families, with their undeniable genetic kinship give coherence to the family Hoplitophryidae.

Notes: SYNOPSIS. Histochemical techniques were used to demonstrate the intracellular distribution of some hydrases, hydrolases, oxidases, and dehydrogenases in Stylonychia pustulata. The hydrase, aconitase, was confined to the mitochondria. Zymohexase activity occurred in the cytoplasm and probably in the mitochondria. The hydrolases, acid and alkaline phosphatases, lipase, and urease, were localized in the mitochondria. Lactic and glutamic dehydrogenases were confined to the mitochondria. Peroxidase and glycerophosphate dehydrogenase were absent.

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. The mating behavior of 16 stocks of Paramecium multimicronucleatum from 12 states has been studied. Mating always follows a decline in nutritive conditions. The evidence indicates that there exists one set of four interbreeding mating types. The period of subculture strongly influences the mating reactions, many stocks mating only long after isolation from nature and culture in the laboratory under the restricted conditions employed. Selfing was observed to occur in many races, usually after long periods of subculture. It first occurred in only a small proportion of the population, later in a larger proportion. The similarities and differences between P. multimicronucleatum and other species of protozoa showing multiple mating types are discussed.

Notes: SUMMARY. A study of the temperature-pressure relationship in oxygen poisoning of Paramecium caudatum was undertaken, as the initial step in defining some of the major factors in in vivo oxygen poisoning. Paramecium was selected because it was relatively simple to culture in a pureline clone, large numbers were readily obtained, and it was large enough to be clearly visible under low magnification. The protozoa were exposed to oxygen pressures of 0 (100%), 15, 30, 45, 60, 75, 90, 105, 120 pounds/inch2 gauge pressure at each of the following temperatures: 1, 5, 10, 15, 20, and 27°C. Exposure was accomplished in a transparent, high-pressure lucite tank which permitted visual observation with aid of a dissecting microscope. It was found at temperatures above 5°C. that oxygen toxicity varied directly with pressure, but below this temperature, with oxygen tensions of 1–2 atmospheres (absolute), oxygen toxicity varied inversely as the temperature. The possibility is advanced that oxygen may be affecting two cellular processes (perhaps enzymatic), one of which is temperature-limited below 5°C. and would, therefore, decrease the death time as the temperature is decreased. Several experiments performed at 3°C. produced a death time intermediate between results obtained at 1° and 5°C.

Notes: SUMMARY. A stock of Paramecium bursaria is described in which the peniculus contains only 8 columns of cilia and associated “granules”. The gullet system is composed of organelle complexes almost exclusively, and incorporates no underlying or transecting extensions of “pellicular fibrillar systems”. A brief discussion is presented on the value of the peniculus as a taxonomic criterion in separating “aurelia” and “bursaria” groups in Paramecium.

Notes: SUMMARY. Strains E, S and W of Tetrahymena pyriformis were examined for their ability to carry out the reactions of the Krebs-Henseleit urea cycle, using growth and enzyme studies. None of the strains was able to grow on either citruliine or ornithine in place of arginine, and proline was as active as citrulline or ornithine in sparing arginine. So little citrulline or arginine was synthesized by cell-free preparations as to be of no significance in the growth or nitrogen metabolism of the ciliates. Slight arginase activity could be detected in homogenates, but no urea was found in cultures. No urease activity could be detected using urea-C14.

Notes: SUMMARY. An eimerian coccidian is described from the flying squirrel, Glaucomys volans, in Florida. It is identified as the same eimerian described by Roudabush from the flying squirrel in Iowa as Eimeria sciurorum. Evidence is presented that Roudabush incorrectly identified the organism. It is renamed as E. parasciurorum nov. sp. Mature oocysts have mean measurements of 29 × 16°, an index of 1.82, are cylindrical with rounded ends, have a dual membrane, and no extra residual body. Oocysts are without micropyle. Four egg-shaped, mature sporocysts in the oocyst have mean measurements of 11.2 × 6.2°, an index of 1.81, contain an oval, granular, intraresidual body and two pyriform sporozoites 10 × 3.2°, index 3.11.

Notes: SUMMARY. Two centrioles, an old one and a new one, are always present in the resting cell. From prophase onward two new ones and two old ones are present. Beginning with the resting stage, five types of centriole life cycles are described and compared with one another: In type 1, both centrioles are elongate; in type 2, the old one is long and the new one, which is short, elongates in prophase; in type 3, both are short, both elongate in prophase, and both, except for their anterior tips, degenerate in late telophase; in type 4, both are long but in prophase their distal ends become free of the rest of the centrioles, these ends migrate to center or posterior end of cell, where, after they produce the achromatic figure and it completes its function in nuclear division, they degenerate; in type 5, both are short and neither elongates at any stage of its life cycle.New centrioles are produced by the anterior ends of old ones. In their first generation, centrioles produce only extranuclear organelles (flagella, parabasals, axostyles, etc.); in their second and later generations, they produce only the achromatic figure (gametogenesis in Trichonympha and reorganization in Barbulanympha and Rhynchonympha are exceptions to this rule).The distal ends of centrioles in some types of cycles are surrounded by centrosomes; in others they are not. In one type of centriole life cycle a small central spindle is present in the resting cell in two genera; in the other types this is not the case.

Notes: SUMMARY. The endogenous development of the life cycle of Eimeria alabamensis Christensen, 1941, occurs in the nucleus of the intestinal cells of cattle. Calves were killed at various intervals after inoculation with infective oöcysts to study the endogenous cycle. Excysted sporozoites were found in the contents or scrapings from the walls of rumen, omasum, small intestine, cecum, and colon. They were found in the cytoplasm of intestinal epithelium at 2 days. Schizonts were found in the nuclei beginning at 2 days, but the number was low by the 8th day. Merozoite numbers usually ranged between 16 and 32. Some host nuclei contained as many as 48 or more, but these appeared to be the result of more than one schizont merging in the same host nucleus. Merozoites were slender, spindle-shaped bodies while still in the schizont walls, but were short with bluntly rounded tips when found in intracellular spaces and crypts. Gametocytes were found as early as the 4th day. Most of the stages of gametogenesis were limited to the lowest third of the small intestine, but in heavy infections some were also found in the cecum and upper colon. Microgametocytes were multinucleate and were more densely stained than the uninucleate macrogametocytes. The ratio of macrogametocytes to microgametocytes in 100 gametes was 78: 22. Oöcysis with “shells” were found in sections of the lower 20 feet of the ileum on the 6th day, which coincided with the shortest prepatent period reported previously. As many as three schizonts or microgametocytes or four or five macrogametocytes or oöcysts could be found in the same host nucleus. The variations in shape of the oöcysts appeared to be dependent on the number of oöcysts crowded into each nucleus.

Notes: SUMMARY. The role of centrioles in achromatic figure production is considered when the number present varies from 1–8. Each centriole after it becomes elongate produces astral rays from its distal end. Some of these rays remain free; some, by joining centromeres, become chromosomal fibers; and some, by joining and growing along those produced by one or more other centrioles, produce the central spindle portion of the achromatic figures. Thus, one centriole may function cooperatively with one to several others in the production of central spindles. But at least two centrioles must be present, and in the proper spacial relation to each other, to form a central spindle; one by itself can form only free astral rays, no central spindle or chromosomal fibers.The flagellated areas (to which the centrioles are anchored anteriorly) play an important role in determining the position of the distal ends of the centrioles with respect to one another, and the position of these ends, in turn, in a large measure, determines the types of achromatic figures produced, particularly the number of central spindles.

Notes: SUMMARY. Observations on binary fission of Lacrymaria olor show that it is a transverse fission. It involves probable intranuclear division of the micronucleus. Both micro- and macronucleus elongate in preliminary stages. Each is ultimately divided as cytoplasmic constriction cuts the spindle fibers of the former, and the connecting, nucleoplasmic thread of the latter.Surging movements of cytoplasm after fission elongate the daughter organisms and move new nuclei to normal, central sites. The anterior proboscis of the posterior daughter regenerates suddenly, complete with coronal cilia. Metachronal waves along ciliary meridians, strongly reversed on the posterior daughter, cause an oscillating movement which pulls the two apart, except for a slender, pellicular thread, ultimately severed. Until broken, this thread connects the rear tip of the anterior animal to the forward end of the proboscis of the posterior one. The organism is semi-quiescent, with proboscis retracted (except spasmodically) throughout fission. After fission the anterior animal quickly begins feeding movements and soon swims away. The posterior animal requires about half an hour before being able to begin feeding and swimming movements.The anterior contractile vacuole of the original animal becomes the primarily active vacuole of the anterior daughter; the posterior one that of the posterior daughter. Missing vacuoles are regenerated by the daughters in about one hour after fission. The division process requires about one hour for completion at 22.4°C.

Notes: SUMMARY. The multiplication rate of Tetrahymena pyriformis HS in proteose peptone medium was measured at 12 temperatures between 18.4°C. and 36.6°C. At the temperature optimum, 32.5°C., the generation time is 2.25 hours. The upper lethal temperature lies between 36.6°C. and 38.0°C. Similarly, a study of Tetrahymena pyriformis GL revealed a temperature optimum for multiplication of 29°C. with a generation time of 3.70 hours. The upper lethal temperature falls between 34.6°C. and 35.4°C. At all temperatures employed the HS strain of organisms multiplies more rapidly than strain GL. Under identical conditions, the two strains have distinctly different growth optima, upper lethal temperatures and growth rates.As measured by multiplication rate the readjustment to a sudden change in temperature (from 18.4°C. to 27.7°C.) is completed very rapidly, with an effective lag time of about 1 hour. Such a shift in temperature gives rise to a small degree of division synchrony during the first and second population doublings which follow. Subsequently, all traces of division synchrony are lost.

Notes: SUMMARY. Test tube cultures of Tetrahymena pyriformis GL in the early maximum stationary phase of growth were used as inocula. After the elapse of a short lag phase a rapid transition to the logarithmic phase of growth was observed in cultures grown on peptone media(4,6). During the early phase of exponential multiplication more cells (as expressed on a percentual basis of the population number) were in the visible stage of cytoplasmic fission than after the elapse of 5 to 6 generations. Analysis of comprehensive data suggests that the higher division index in the early logarithmic phase of growth is not the expression of a synchronization of cells in metabolic respects but rather indicates a prolongation of the stage of cell fission during this phase.

Notes: SUMMARY. Ochromonas malhamensis (Pringsheim strain) can be grown above 35.5°C.; below 35°, the previous chemically defined medium supports dense growth. The B12 and thiamine requirements rise steeply with temperature, and growth promotion by folic acid emerges; folic acid spares the enhanced B12 requirement. B12 is spared also, perhaps wholly bypassed, by purines + pyrimidines + amino acids (below 35°, exogenous purines, pyrimidines, and folic acid have little effect). Requirements also emerge for glycine (spared by serine), valine and isoleucine (their ratio is critical; leucine and threonine assist in maintaining a good balance), and, at very slightly higher temperatures, phenylalanine, tryptophan, cystine, and lysine. Requirements for Mg, Fe, Zn, and Mn appear to rise steeply with temperature; metal toxicities have to be circumvented carefully. The proportion of histidine + arginine to carbohydrate has to be increased, and a Krebs-cycle component such as succinic acid becomes stimulatory. At 36.3–36.7°, a further supplement of crude natural materials such as an autoclaved suspension of Ochromonas cells is needed. Relevance of these findings to fever stress in vertebrates, general mitochondrial function, and repair of radiation damage, is discussed.

Notes: SUMMARY. According to Kahl the trichostome genus Trichopelma may be considered to include five species: T. sphagnetanim, T. eurystoma, T. euglenivora, T. opaca, and T. torpens. A sixth species is added in the present account. The following constant characteristics distinguish it from the five earlier described ones: total lack of trichocysts; differences in the morphology of the body surfaces; dissimilarity of the upper and lower surfaces in shape (one plane, the other convex), in ciliation, and in number of cuticular furrows; unique location of the contractile vacuole.

Notes: SUMMARY. Isospora citelli n. sp. is described from the rock squirrel, Citellus variegatus Utah, from Grand Canyon National Park, Arizona. Its oocysts are subspherical, 22.4 by 21.5 μ, with a smooth, two-layered wall, an oocyst refractile globule and a sporocyst residuum, but without a micropyle or oocyst residuum.

Notes: SUMMARY. Leptomonads of Leishmania tarentolae were grown continuously in a defined medium containing: inorganic salts', glucose, hemin, 17 amino acids, purines and pyrimidines, and a mixture of vitamins of the B group. In this medium the population of organisms reached about 20 to 50 million per ml. alter 1 week at 27°C. Only slightly better growth occurred in a partially defined medium containing bovine plasma fraction V. In earlier experiments, however, omission of the plasma fraction resulted in decreased growth, and under these circumstances cholesterol or lecithin had growth-stimulating effects. In later experiments in the fully-defined medium no effect of these lipids could be found. The leptomonads were shown to require at least the following substances: inorganic salts; a source of purines and pyrimidines; tryptophan and the nine other amino acids essential for the growth of rats, glutamic acid, tyrosine, proline, serine, one or more of the group alanine, glycine and aspartic acid; folic acid, biotin, pantothenic acid, nicotinamide, riboflavm, thiamine, and either pyridoxine plus choline or pyridoxal or pyridoxamine. Choline at 2 × 10−5 m gave optimal growth in the presence of pyridoxine at 1 × 10−5 m. In a medium with a suboptimal concentration of choline (0.4 × 10−5 m) the leptomonads grew through nine transfers but they were mostly somewhat rounded and aflagellate.

Notes: SUMMARY. Trichopus lachmanni n. sp. possesses, in common with other members of the family Dysteriidae, a fixation organelle composed of vesicles and a secretory ampoule. But no “foot-like” appendix exists in this species, and the ampoule opens at the bottom of an antapical pit which bears a short fringe of membranelles derived from the somatic ciliature. The vibratile fringe participates in the spinning of the glutinous secretion which temporarily fastens the organism to the substrate. This specialized ciliature is characteristic of the genus Trichopus which was created by Claparède & Lachmann for a species, T. dysteria, which, though insufficiently described, is certainly different from T. lachmanni.

Notes: SUMMARY. Various species of ciliates are characterized by the formation and accumulation in the cytoplasm of mineral concretions which are refringent, isotropic or anisotropic. These cytoplasmic inclusions most often are composed of calcium carbonate; in several species, however, their nature remains partially or even totally undetermined. The isotropic calcium-containing concretions often exhibit a definite shape; the calcium carbonate in this case appears to be bound to an organic substrate. The physiological role of the calcic concretions is not known; their characteristic presence in a given species is not necessarily related to ecological conditions. In a few species the calcification is localized in definite structures: spicules, skeletal plates, or otoliths of organelles supposedly sensory in nature.

Notes: SUMMARY. The combination Tween 80 and cholesterol replaced blood serum as a requirement for the cultivation of Tritrichomonas foetus. Choline + potassium glycerophosphate enhanced growth in the presence of Tween 80 + cholesterol. A method for ensuring adequate cholesterol suspension-an essential factor for consistent growth-is described.

Notes: SUMMARY. High variability within cultures of Tritrichomonas batrachorum (from Bufo boreas halophilus, Rana catesbeiana, and Rana pipiens) casts doubt on the validity of length measurements for species designation.The morphology differs from that described previously. The axostylar capitulum is a complex structure with a preblepharoplastic portion and a perinuclear cup spreading laterally in curved membranes ending in filaments. The parabasal apparatus is Y-shaped with a very short base.Two types of amoeboid activity occur. Filopodia are used for anchorage. Their bases migrate and the filopodia may fuse and reseparate as in foraminifers. Ingestion is an amoeboid process utilizing lobopodia. Food adherent to a lobopod is invested in a food cup at the surface. Ingrowth of the lip of the food cup forms the food vacuole, or in cases of cannibalism, constricts the prey and forms a food tube pushing a vacuole before it. Repeated, this produces an alternating series of vacuoles and tubes. There is a pseudo-amoeboid degenerative process in which the flagella, withdrawn into the cytosome, continue to move and produce non-functional lobopod-like protrusions.An actual cytostome has not been observed, but there is a region of reduced staining intensity ventral to the axostylar capitulum.

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 oocysts, sporulation process, and endogenous stages of Eimeria raillieti (Léger, 1899) Galli-Valerio, 1930 from the slow-worm, Anguis fragilis, in England are described. The oocysts average 18 × 15 μ. Schizonts, microgametocytes and macrogametocytes were found in the ileum, and macro-gametocytes alone in the duodenum.

Notes: SYNOPSIS. Zooxanthellae in pure culture, exposed to continuous light, release free O2 in amounts varying with time and cell number. Zooxanthellae exposed to alternate light and dark produce essentially as much O2 as in continuous light. Those in continuous dark do not yield free O2; rather, they draw from the medium's residual O2.Both the anemone Condylactis and the scyphozoan Cassiopeia are markedly phototactic. Kept in total darkness, both species show a dramatic numerical diminution in zooxanthellae. During 24 days of darkness, the mean total number of zooxanthellae in the individual Condylactis body was reduced from 26 million to ∼ 1 million. Specimens so bleached lost phototaxis.It is suggested that each species of zooxanthella host animal has its own specific light needs, which it caters to in various ways: (a) early selection of position, as with planulae or other freely motile larval forms; (b) gross body movement or posturing, as with anemones, medusae, and worms; (c) possession of light-filtering pigments, as with colored corals and molluscs; (d) possession of light-concentrating devices, as with tridacnids; (e) possession of highly contractile and differentially light-absorbing tissues, as with most coelenterates and some molluscs.Susceptibility of marine invertebrates to zooxanthellae infection may be related to the known paucity of nitrates and phosphates in tropical seas, a situation possibly inducing the free-swimming gymnodinioid forms to enter animal tissues where catabolic products are available to them. Zooxanthellae are reported from sessile marine invertebrates taken at depths of 100–116 fathoms.

Notes: SYNOPSIS. All of 99 adult English house-sparrows, examined in the St. Albans area of Hertfordshire, England, were found to be infected with the organism previously defined by Garnham (1950) as Atoxoplasma. Young birds were found to become infected while still in the nests and as early as 6 days after hatching; there was no evidence to suggest that the parasite was transmitted through the egg. Within a few weeks of leaving the nests, all of 150 fledgling sparrows examined were heavily infected and several trapped birds died from massive infections.All stages of schizogony were found in the lymphoid-macrophage cells of the spleen, bone marrow and liver of these birds; later, as the schizogonic cycle abated, gametocytes developed in similar cells of the liver, lungs and kidney. These gametocytes are of the Eimeria type: the zygote nucleus divides to produce an asporous and polyzoic oocyst containing a large number of sporozoites, and after the rupture of the oocyst these sporozoites invade the lymphocytes and monocytes of the peripheral blood.Transmission of the parasite in the sparrow is thought to take place after the ingestion of infected mites (Dermanyssus gallinae) by the young birds in the nests: unchanged sporozoites were found in smears of these mites that had been fed on infected sparrows. Transmission experiments were impossible due to the complete lack of clean sparrows.The taxonomic status of Atoxoplasma is discussed. The type of life cycle and the production of asporous, polyzoic oocysts indicate inclusion of this parasite in the Order Coccidiida, Family Eimeriidae, Sub-Family Cryptosporidiinae Hoare, 1933. After comparison of the two genera, the author concludes that Atoxoplasma must be regarded as a synonym for Lankesterella. Some previously described species of Atoxoplasma are, therefore, transferred to the genus Lankesterella.The name Lankesterella garnhami nov. sp., is proposed for the parasite in the English sparrow (Passer domesticus domesticus), and Lankesterella serini nov. sp., for that in the canary (Serinus canarius).

Notes: SYNOPSIS. Darkness and O2-lack promote formation of a pheophytin-like pigment from chlorophyll in Euglena gracilis in an acidic medium. Dinitrophenol (DNP) produces similar but more drastic pigment alterations in aerated and illuminated cells. The extent of pigment decay was dependent on DNP concentration and external pH. Since volume expansion and inhibition of the contractile vacuole were also noted, it is suggested that pheophytin formation is secondary to hydrogen ion influx from the external medium. Major structural alterations of the chloroplast accompanied the pigment changes.Pentachlorophenol, iodoacetamide, Na fluoride, and Na azide produced similar pigment changes. Malonic acid and fluoroacetate were ineffective under the conditions described. However, in the dark, cells treated with fluoroacetate formed pheophytin rapidly. These effects are discussed in relation to the maintenance of intracellular [H+].

Notes: SYNOPSIS. The heterotrophic, phototrophic, and phagotrophic nutrition of the chrysomonad flagellates Ochromonas malhamensis and O. danica were compared. Unlike O. malhamensis, O. danica, which is much richer in chloroplast pigments, grew readily photoautotrophically in a substrate-free medium in 5% CO2. Utilization of bound biotin in bacterial (Thiobacillus) bodies served to demonstrate phagotrophy in both flagellates. This nutritional versatility suggests that this group of flagellates will be exceptionally valuable for studying the evolutionary steps connecting photoautotrophy, heterotrophy, and phagotrophy.

Notes: SYNOPSIS. In a synthetic medium containing 57 compounds, including cholesterol, Trichomonas gallinae and T. gallinarum require 3 factors for growth and acid fermentation of maltose: (1) factor R, found in the protein contaminating some samples of ribonucleic acid, and in other isolated proteins such as conalbumin, γ-globulin, and bovine albumin fraction V; (2) factor T, found in Trypticase and in the same isolated proteins, but with activity at 4 times the dose required for factor-R activity, may be a large peptide containing proline; (3) factor S, found in serum, was replaceable by a saturated and an unsaturated fatty acid, each inactive alone. Only C14 through C18 saturated fatty acids were active over a range of 0.058 to 2.34 μm per tube in the presence of oleic acid, while C18 through C22 unsaturated fatty acids were active in the same range with palmitic acid as the supplement. The unsaturated fatty acids were toxic at the largest dose. All fatty acids were not equally active. Surface-active agents containing mixtures of fatty acids also replaced serum. A 4th factor, found in serum, stimulates the rate of growth as shown by cell counts at 3 days of incubation. T. gallinarum, T. foetus, and a trichomonad from a pig's nose responded to the same supplements when grown on another synthetic medium.

Notes: SYNOPSIS. Differences in temperature-tolerance, generation time, nutritional requirements, osmoresistance, pigment production, and sensitivity to high hydrogen or hydroxyl ion concentration have been observed among varieties, and among mating types within varieties of Tetrahymena pyriformis. The usefulness of these differences to taxonomists and geneticists is discussed.The nutrition of a temperature-tolerant strain, mating type II, variety 1, was given special attention and a chemicallydefined medium devised to support rapid growth at 35d̀ C. At 40d̀, growth in this medium failed, but was good in a crude medium. Temperature factors are suggested. Permeability of this ciliate, as inferred by utilization of nucleotides, was high.

Notes: SYNOPSIS. Eight strains of Tetrahymena pyriformis were examined in multiple daily isolation series over ∼ 800 generations. Dead and defective lineages appeared in all clones. In 7, the defective sub-lines appeared at a constant characteristic rate; the 8th showed an increasing rate of production of two defects. A breeding analysis of certain persistent morphological and growth rate variants suggests that the variations derive from macronuclear alterations. The relationship between these cellular changes and “senility” in metazoa and other protozoa is discussed.

Notes: SYNOPSIS. An acetone-insoluble yeast fraction required for axenic growth of P. aurelia, stock 51, variety 4, sensitive, after fractionation contained at least 3 essential components: (1) one soluble in perchloric acid and completely replaceable by a mixture of ribosides or ribotides; (2) one inactivated after digestion with trypsin, chymotrypsin or papain. Proteose-Peptone restored activity to this preparation, which suggests a peptide requirement; and (3) one not yet characterized.As for the purine and pyrimidines, these combinations, in decreasing order of activity, supported growth: guanosine + cytidine, guanosine + uridine, guanylic acid + cytidylic acid, and guanylic acid + uridylic acid. Each combination was maximally effective when the molar purine: pyrimidine ratio was ∼ 0.4. On a molar basis, the minimal riboside combinations were ∼ 1.3 × more active than the ribotides.Sparing of the purine and pyrimidine requirement was also investigated. In the presence of limiting amounts of guanylic acid, the following compounds, in decreasing order of activity, had sparing activity: deoxyguanosine, inosine, xanthosine, adenylic acid, and guanine. Adenine, adenosine, and deoxyadenosine were inhibitory under the test conditions. The requirement for cytidylic acid was spared by deoxycytidine, uridine, uridylic acid, deoxyuridine, thymidine, thymine, and uracil, in descending order.

Notes: SYNOPSIS. In reviewing 25 years of work on Tetrahymena, the author describes early difficulties experienced by himself and others in developing a chemically-defined medium and in defining the taxonomy of T. pyriformis. With identification of its essential requirements, a variety of nutritional studies revealed the close resemblance between the metabolic pathways of this ciliate and those of the chick and rat. This suggested studies on the effects of gamma radiation and the effect of antibiotics.Attention then turned to the puzzle of the absence of conjugation in all strains of T. pyriformis then maintained in laboratories. The observation that these strains were all amicronucleate led to the discovery of mating types (with D. F. Gruchy). This brought up the problem of what constitutes a species and how it might be solved in T. pyriformis where clearly defined groups are set off from other similar groups (varieties) by a breeding barrier.Another problem is whether a life cycle exists in this ciliate and if so, the role amicronucleate strains play in this cycle.The origin and obvious evolutionary success of these “genetically dead” strains are other problems that are considered.The search for nutritional markers for genetic experiments inspired large-scale collections, including some from tropical habitats. Strains were found which differed in serine and pyridoxine requirements. Genetic analysis was hindered by the high lethality following conjugation, unsatisfactory mating behavior in some clones, and the complete absence of autogamy, the latter making it difficult to obtain homozygous clones. The use of x-radiation yielded haploid individuals; when these were mated with diploid clones the resulting haploid progeny proved that the genes controlling mating type and pyridoxine synthesis resided in the micronucleus.Genetic analysis of the serine and pyridoxine mutants supports the idea that T. pyriformis is more of an outbreeder than an inbreeder. Left for the future is an extension of our knowledge of the breeding system of T. pyriformis and ultimately to examine critically the factors responsible for the success of this ubiquitous ciliate.

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. During encystment of Colpoda cucullus (O. F. Müller) the respiratory rate decreases from about 11.3 × 10-5μl. O2/hr. (mean value for active form) to about 1.3 × 10-5μl./hr. (mean for unstable cyst); the process takes about 24 hrs. At the same time the activity of the contractile vacuole is stopped, but there is no correlation in time between the two processes: when respiration is inhibited by 1/2–2/3 the vacuolar activity is hardly changed. The respiration of unstable cysts remains approximately constant at least for 4 weeks. Experiments with methylene blue suggest that inhibition of respiration at encystment may be due to inhibition of terminal oxidase.

Notes: SYNOPSIS. Two isolates (“A” and “B”) of Trypanosoma lewisi from the same rat stock source were serially transferred in calorically-restricted mice supplemented daily with normal rat serum. The “A” strain was transferred consecutively through 300 mice over a period of more than 3 years and was voluntarily discontinued. The “B” strain died out spontaneously after 43 consecutive passages in mice. The developmental histories of these 2 isolates were analyzed and compared with respect to duration of the parasitemic period, interval to the next subsequent passage in mice, day of death of each host animal, proportion of host animals that died, intensity of parasitemia in mouse tail blood, interval required for development of the observed maximal parasitemia, and duration of maximal parasitemia.“A” appeared to have become progressively adapted to the mouse as judged by a decrease in parasitemic period with successive transfer associated with a progressive increase in trypanosome population, and declines in the interval required for development of the observed maximal parasitemia and in the duration of this maximal response. There did not appear to be any correlation of the percentage of animals that died with any other factor. The “B” strain did not appear to have adapted itself to mice as judged by the foregoing criteria.

Notes: SYNOPSIS. The Indian race of Blepharisma undulans described in this paper measures 150 μ in length. The macronucleus consists of 5–7 nodes, all of equal size. During binary fission, condensation of macronucleus is followed by its elongation and a thinning of the middle region which breaks with the division of the animal. It later attains the typical vegetative form.During conjugation 7 or 8 micronuclei pass through the first pregamic division, 5 to 7 through the second pregamic division and one product of the second division takes part in the third division. The rest degenerate. At the same time, the macronucleus also starts degenerating. After the synkaryon has divided twice, the conjugating pairs separate. Of the 4 products, 3 become macronuclear anlagen and one, micronuclear anlage.The micronuclei divide asynchronously both during binary fission and during conjugation. There is apparently considerable diversity in the structure and behaviour of the macronucleus and micronuclei in the different races of Blepharisma undulans.

Notes: SYNOPSIS. In cattle fed a high-starch diet, species of Entodinium and Diplodinium ingested associated ruminal bacteria. Stained preparations of diluted rumen contents showed Entodinium caudatum, E. minimum, E. dubardi, (syn. E. simplex), E. longinucleatum, E. bursa, E. nanellum, E. exiguum, and E. vorax contained gram-positive diplococci. Starch grains with adherent gram-positive diplococci were observed within Entodinium spp. Diplodinium ecaudatum forma ecaudatum, D. ecaudatum forma caudatum, D. neglectum and an unidentified species of Diplodinium also ingested ruminal diplococci. Bacteria were isolated from mixed species of Entodinium by washing and culturing the protozoa in a starch feed-extract agar medium. The strains isolated from the ciliates were gram-positive diplococci, 0.8 times 1–1.5 μm, which attached themselves to starch granules and were able to digest the starch. Conclusive evidence of bacterial ingestion by the oligotrichs was obtained by providing the bacterial cultures to Entodinium species (E. dubardi and E. minimum) which had been starved 24 hr. Gram-stained preparations showed the ciliates readily ingested the bacteria. The amylolytic cocci utilized by Entodinium spp. were identified as Streptococcus bovis.

Notes: SYNOPSIS. Lankesterella corvi n. sp. (Coccidia, Eimeriidae, Cryptosporidiinae) is described from the rook, Corvus f. frugilegus L. in England. It was found in 36 of 196 fledged rooks less than 1-year old, but not in 25 nestlings or 38 adults. It was not found in 71 jackdaws (C. monedula spermologus) or in 110 other birds of 16 species.Mature sporozoites were found in the erythrocytes and occasionally in other blood cells. They were 6.2 times 2.5 μ, with a central, band-like nucleus, and cytoplasm which failed to stain with Giemsa's stain. Gametogonic and sporogonic stages, found in the bone-marrow of one bird, resembled corresponding stages of Eimeria.A fledgling rook was infected experimentally by inoculation of a blood and tissue suspension from an infected bird. Sporozoites appeared in its blood 4 days after inoculation. They appeared to increase slightly in size and their cytoplasm lost its initial affinity for Giemsa's stain during the next few days. Engorged mites (Ornithonyssus sylviarum) from the experimentally infected rock contained unchanged sporozoites but no developmental stages of the parasite. A canary could not be infected by intraperitoneal inoculation and feeding of such mites.

Notes: SYNOPSIS. A dichotomous, analytical key is offered for use in recognition and differentiation of the 26 orders and suborders belonging to the two subclasses of the single class Ciliata of the subphylum CILIOPHORA. The basic terminology employed in these brief characterizations, usable in systematic studies of ciliates in general, is defined first, and a plea is made for a more uniform vocabulary, especially in reference to structures which are without doubt homologous throughout the several higher ciliate taxa. Particular emphasis is placed on the all-important features in the oral area; many of these are figured as well as being described in words.Both the key and the definitions are essentially the first to be offered since Kahl's monographic work on the ciliates published in 1930–1935. They are demanded by the great accumulation of new pertinent data in the protozoclogical literature of the past 25 years.

Notes: SYNOPSIS. The flagellate, Peranema trichophorum, has been studied in the electron microscope by thin-sectioning techniques. The flagella have the fibrillar pattern typical of cilia and flagella, but accessory structures including tapered, intraflagellar rods, striated, layered material on the outside of the membrane, and mastigonemes are present. In the near basal region of the flagellum, there is a swelling of the shaft which is correlated with the absence of the two central flagellar fibrils. The basal portion of the intraflagellar material is structurally and locationally similar to the basal parts of the flagellar fibril bundle; this similarity suggests that the two structures originated from similar precursors and that two kinetosomes comprise the light microscopist's blepharoplast in this organism.The ridged pellicle is composed of 3 membranes, only two of which follow the contour of the ridges. Several filaments 21 mμ in diameter are localized under the low point of each ridge, and a single, larger fibril which has a periodic structure is often located beneath the high point of each ridge.The cytostome and structures associated with it are described and discussed in relation to food taking. The pharyngeal rods are cross-connected and each is composed of numerous tubular elements surrounded by a denser, homogeneous layer. A system of membranes is attached to the rods and extends anteriorly.The nucleus contains two large nucleoli, numerous rod-shaped, membrane-limited bodies which appear similar in structure to bacteria, and a smaller granular component.Other organelles are briefly described including mitochondria, Golgi bodies, vacuoles, and endoplasmic reticulum.

Notes: SYNOPSIS. Materials within the endoplasm of both the protomerite and deutomerite may be displaced and stratified by ultracentrifugation. Animals are not killed by this treatment, and in time a redistribution of stratified materials may occur. The electron microscope reveals numerous ultramicroscopic folds in the surface envelope which is composed of 3 membranes; the outer and middle cover the surface of the folds while the inner one continues as a smooth membrane over the ectoplasm. The contact surfaces of animals in syzygy do not show the small folds to be interlocked; instead, they are in fold-to-fold contact. Numerous relatively dense bodies which appear to be filamentous are sometimes observed immediately underneath or within the middle or inner membrane. Within the ectoplasm is an ultramicroscopic net-like fibrillar structure much denser than the surrounding cytoplasm. This system of fibrils is composed of anastomosing elements varying from ∼ 50 to 200 Å in diameter. Certain of the larger fibrils are directly attached to the surface envelope at positions between the folds. A second filamentous structure within the ectoplasm appears to be tubular. Elements of this system also appear to join and penetrate the surface envelope by means of pores.A large amount of gelatinous secretion forms at the surface of the sporont; as it glides forward a trail of mucous is left behind. The actual mechanism involved in the gliding movement was unobserved, but evidence is lacking to support the view that the gliding movement is engendered by posteriorly directed “jets” of mucus.

Notes: SYNOPSIS. Vorticellas were subjected to achromycin, polymyxin, and mixtures of penicillin-streptomycin to remove bacterial contaminants. Although achromycin and polymyxin were most effective in controlling bacteria isolated from vorticella cultures, they proved too toxic for practical use. However, certain dilutions of penicillin-streptomycin were tolerated by vorticellas and, therefore, were incorporated into the axenizing procedure. Yeasts did not yield to the antibiotics and had to be removed by washing and dilution. Sterile vorticellas were finally obtained by transfer of groups of individuals through 6 washes. One of these, the 4th, lasted 8 hours and contained diluted penicillin-streptomycin.

Notes: SYNOPSIS. The interphase nucleus of Lesquereusia spiralis, a testate rhizopod, 20–25 μ in diameter, contains 40–50 endosomes and a diffuse granular reticulum. Onset of nuclear division is marked by a cessation of pseudopod activity. Prophase changes include increase in size of the nucleus, disappearance of the endosomes except the peripheral ones, formation of 175–200 chromosomes from the reticulum, and the appearance of spindle fibers. By the end of prophase a well formed equatorial plate is present. The metaphase nucleus is slightly smaller and elongated; the chromosomes remain distinct. In anaphase the nucleus continues to elongate along the polar axis; the chromosomes apparently split lengthwise and polar caps appear. The nucleus elongates further so that by telophase it has become hour-glass shaped. The spindle fibers are now twisted. Separation of the nuclei takes place in the neck region. The nuclear membrane is unbroken during the process and peripheral endosomes are present at all stages. Total time for mitosis averages 45 minutes.

Notes: SYNOPSIS. Three gregarines are described from the digestive tracts of marine crustacea from Bombay, India. These are Carcinoecetes etisi n.sp. from Etisus laevimanus, C. matutae n.sp. from Matuta lunaris, and Caridohabitans setnai n.gen., n.sp. from Peneus semisulcatus. Various life history stages are reported.

Notes: SYNOPSIS. In various ciliates the contractile vacuole is a permanent organelle, delimited by a differentiated cortex.The cortex is made up of a dense reticulum of anastomosing tubules limited by a smooth membrane, and vesicles. This “spongiome” can be considered as a localized and specialized condensation of the endoplasmic reticulum.

Notes: SYNOPSIS. Two species of flagellate parasites, Herpetomonas muscarum (Leidy 1856) Kent 1881 and Crithidia luciliae (Strickland 1911) have been isolated in pure culture from the fly, Phaenicia sericata. Laboratory-reared Musca domestica were infected with each of the species. These two species have often been confused, the latter being regarded as “cysts” of the former. H. muscarum is long and slender and occurs actively swimming in the midgut of the host. C. luciliae is short and truncate and occurs mainly in the hindgut where it is often attached to the gut wall. C. luciliae grows readily and abundantly in culture and outgrows H. muscarum in mixed cultures. Attempts to infect Aedes aegypti and Culex pipiens with C. luciliae failed while control feedings of these mosquitoes with Crithidia fasciculata produced infections.

Notes: SYNOPSIS. Trimastigamoeba philippinensis Whitmore 1911 from Florida was cultured in the laboratory at 22 to 25° C. on a modified Bunting's agar medium overlaid or not with Neff's ameba-saline. Studies of its general morphology, transition from ameboid to flagellate phase and vice versa, encystment, and excystment were made. In general, Whitmore's observations are confirmed, except for his conclusions concerning the number of flagella and whether or not there is a rhizoplast. The flagellate phase has two mastigonts, each composed of a pair of flagella attached to a basal granule (blepharoplast). Intermediate stages in the development of the mastigonts may have caused Whitmore to decide that a tri-flagellar phase was the usual condition. The two mastigonts are not at any time attached to one another, nor to the nucleus, nor is there any evidence of a rhizoplast or rhizostyle. In the flagellate phase the bases of the mastigonts are closely surrounded by an anterior, gullet-like invagination, posterior to which the blepharoplasts rest adjacent to the nucleus. The four flagella extend 20 to 25 μ beyond the anterior limit of the pocket. Detailed descriptions of the morphologies of the ameboid and flagellate phases are given to supplement the morphology described by Whitmore. Possible affinities to other amebo-flagellates are discussed. It is concluded that the organism is generically and specifically distinct; and while its name is erroneously descriptive of its flagellate phase, it is taxonomically valid.

Notes: SYNOPSIS. The organism used in the experiments fits Pierson's satisfactory description for Euplotes eurystomus. The mating behavior of 90 stocks of E. eurystomus collected from west Japan was studied. Mating occurs only after a decline in nutritive conditions. When the stocks were mixed together, two at a time, in all possible combinations, mating took place in all the mixtures. Mating occurs in the evening or the morning after mixing. An agglutinative reaction does not precede mating; but before pair formation, characteristic pre-pairing behavior is observed. Selfing is found in all the stocks, usually after the log-phase of the growth curve. Culture fluids from various cultures have no detectable capacity to induce selfing, but some of them can suppress selfing. The latter occurs only in specific combinations. Controls mixed with distilled water instead of culture fluid always contain selfers. From the results of such experiments, it is possible to classify the stocks into 9 types, so that stocks of the same type have the same character with respect to suppression of selfing. The culture fluid from type II suppresses selfing only in animals of type I, type IV acts only on type III, VI on V, VIII on VII, and VII on both V and VI. The reciprocal actions also occur, i.e., fluid from I suppresses selfing of type II, etc. The origin of the two mating members of a conjugating pair was traced by making mixtures of normal animals of one type with morphologically abnormal animals of another type. The latter have a distinct swelling at the left margin of the body. Such mixtures (I × II, V × VI and VII × VIII) yield conjugating pairs of normal mated with abnormal animals, i.e. cross-conjugating pairs, in 86–94% of the animals. Mixtures of type VI with VII yield a smaller percentage (48%) of cross-conjugating pairs. Mixtures of two cultures belonging to the same type, (II × II, VI × VI and VIII × VIII), in which selfing is not suppressed, yield 42–50% conjugating pairs of normal with normal, (selfing of the normal culture), and 32–45% conjugating pairs of abnormal with abnormal, (selfing in the abnormal culture). Mixtures of two cultures belonging to diverse types in which selfing is not suppressed (I × V, I × VIII, II × III, II × VII, II × IX, III × V, III × VI, III × VIII, IV × VI and VI × IX), yield 36–48% conjugating pairs (selfing) of normal with normal, and 26–50% conjugating pairs (selfing) of abnormal with abnormal. Interbreeding between two types thus normally occurs only when culture fluid of each type inhibits selfing by animals of the other type. These two types, which interbreed freely, may be considered as complementary mating types. The mating types of E. eurystomus thus fall into 5 varieties so that each one (except the fifth) has two complementary mating types. The mating types are numbered I and II in variety 1, III and IV in variety 2, V and VI in variety 3, VII and VIII in variety 4, and only IX in variety 5. Intervarietal mating does not occur in many combinations, but exceptionally it occurs between types V and VII, and between VI and VII. These hybrids become senile and finally die.

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.