ALBERT

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

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

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

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

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

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

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

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

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

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

Notes: SUMMARY. In water taken March 3, 1956, from a tributary of the Amazon River, near Leticia, Colombia, an abundant ciliate fauna included large numbers of a species of Euplotes. Cursory examination showed a pronounced left wing like that of E. novemcarinatus Wang. Careful study, however, revealed a distribution of peristomal membranelles and peristomal morphology more like that of E. euryostomus Wrzesniowski. The positions of ventral cirri resemble those of E. woodruffi Gaw. The two right caudal cirri are furcated, as are those of the first two above-mentioned species; but the five anal cirri are not. The C-shaped macronucleus, like that of E. aediculatus Pierson, has the upper left part of the “C” somewhat depressed. A large organism, it averages 155 μ long by 130 μ broad, length ranging from 87 μ to 203 μ, and width from 67 μ to 194 μ. It is presented as Euplotes leticiensis n. sp.

Notes: SUMMARY. Following a brief historical review and critique of the main theories of amoeboid movement, the recent work of Goldacre and Lorch, relating plasmagel contraction to the folding and unfolding of protein molecules, is discussed; and some new observations are presented concerning the behavior of the plasmagel in amoebae vitally stained with neutral red. Similarities between contraction of vertebrate muscle and amoeba plasmagel are discussed, and a summary of recent work suggesting that adenosine triphosphate and actomyosin-like proteins may be involved in amoeboid movement is given. A re-examination of the meaning of the terms plasmagel and plasmasol indicates their relative nature denoting only comparative degrees of viscosity. Recent observations as to the nature of the plasmalemma are reviewed, and evidence is presented for the existence of an external slime layer in Amoeba proteus (not in all amoebae), which slides over the visible pellicle carrying adherent foreign particles forward from the precaudal region. The inadequacy of the contracting gel tube theory for explaining many types of protoplasmic streaming is pointed out.

Notes: SUMMARY. Tillina magna is a large holotrichous ciliate, of the family Colpodidae, which normally forms resting cysts. These cysts, when formed in their natural environment, withstand drying. Active animals have been excysted from dirt collected more than 10 years ago. However, until recently, laboratory work on these, as well as on most other ciliate cysts, has been done on wet cysts. A method is described for producing viable dry cysts under laboratory conditions. It consists essentially of inducing the tillinas to encyst on prepared sections of grass stems. In this way dry cysts have been formed which are viable up to 4 months. These cysts, when first formed, can be activated simply by the addition of water. Cysts which are no longer responsive to water alone may sometimes be induced to excyst by the addition of lettuce infusion. Cysts withstand extremes of temperature from -5°C. to 45°C. These facts have some bearing on the question of the factor or factors causing excystment.

Notes: SUMMARY. A study has been made of the number and morphology of the chromosomes of five species of malarial parasites as seen in living material with phase contrast microscopy. Plasmodium knowlesi, of monkeys, is essentially similar to other primate malarial parasites previously studied, having two chromosomes of unequal length. P. lophurae, from ducks, P. relictum from pigeons and sparrows, and P. floridense from a lizard all have two small chromosomes of equal size. These facts, with ether data, indicate that the genus may consist of two species complexes. P. berghei, studied in white mice and rats, has a karyotype similar to the avian and saurian malarial parasites. The suggestion is made that P. berghei, on a basis of chromosome pattern and other characteristics, is probably more closely related to the avian and saurian species of Plasmodium than to other mammalian species.

Notes: SUMMARY. The adaptation to fatty acids by Polytoma depends upon two mechanisms: 1. The induced synthesis of fatty acid oxidase which precedes growth. 2. A long-term physiological adaptation spanning several cell generations which results in an increase of the initial rate of growth.Analysis of the long-term adaptation shows that the adaptation does not result from the selection of fast-growing mutants. The generation time on butyrate of unadapted cells is initially ca. 24 hours and it is reduced to ca. 10 hours after the second subculture in butyrate medium. Adaptation to butyrate results in a simultaneous adaptation to caproate.

Notes: SUMMARY. A survey of protozoa in four water samples from Colombia, South America, yielded 84 species identifiable to genus or to species. Three of the collections were from the Amazon River and a tributary in the vicinity of Leticia, at the southern tip of the country. The fourth was taken near the high Andean town of Medellin in central Colombia.All four subphyla are represented. Forty ciliophorans, 26 mastigophorans, 17-sarcodinians, and one sporozoan are included. Of the ciliophorans all but one are euciliates in three orders. The exception is a suctorean. Two classes, and six orders of mastigophorans are represented; one class, and two orders of sarcodinians; and one class, one subclass, and one order of sporozoans. Eleven suborders, 33 families, and 49 genera are exemplified.Other protozoa seen, but not identified to generic or specific accuracy, are omitted.

Notes: SUMMARY. The division cycle was followed in four strains of Blepharisma undulans. Animals were fixed and stained at regular intervals from the end of one division through completion of the next.A comparative study of the present findings and those in the literature shows that in all strains in which the macronucleus is nodulated there is a similarity in the events that occur during division. These include a loss of some of the chromatin material, a fusion of macronuclear nodes into two masses, and a subsequent fusion of these two masses into one large, centrally located mass. This, in turn, elongates and divides into two daughter nuclei which either are nodulated at the time of separation or become so shortly after the division into daughter nuclei.Great variation exists, among different strains, in the number of macronuclear nodes present. This fact, coupled with knowledge of nuclear morphogenesis during the division cycle, renders macronuclear form of little taxonomic value at infrageneric levels.

Notes: SUMMARY. A rich source of supply of Pelomyxa palustris has recently been found. The findings and views of previous investigators on the geographical and seasonal distribution, longevity in the laboratory and reproduction of this organism are reviewed and discussed. Clone and mass cultures were successfully obtained in Carrel flasks with Spirogyra as food. Feeding is an extremely slow process so that this Pelomyxa is incapable of capturing and ingesting actively motile organisms under ordinary circumstances. Multiplication is solely by simple or multiple plasmotomy.

Notes: SUMMARY. Some of the unusual types of sexual behavior in Trichonympha are considered: cytoplasmic incompatibility of gametes as shown in the fertilization process, pronuclear incompatibility, independence of pronuclear and cytoplasmic incompatibilities, loss of extranuclear organelles of male gamete, the formation of gametes with no chromosomes, those with the diploid number, and those with numbers between these extremes.

Notes: SUMMARY. The various sexual processes in each of ten genera of protozoa of Cryptocercus have been correlated with the molting period of their host in days beginning with 50 days before ecdysis and ending 3 days after ecdysis. Some genera begin the gametogenesis portion of their sexual cycle much earlier in the molting period than others. Gametogenesis in some genera is haploid, in others it is diploid; in some it is a short process, requiring only a few hours for completion; in others it requires several days for completion. Not counting Leptospironympka and Macrospironympha, meiosis occurs after ecdysis in 6 genera and before in two. The fertilization process in some genera is too involved to make possible a simple summary. The time when gametogenesis, fertilization, and meiosis occur in the molting period of the host seems to be determined by the nature of the various genera of protozoan parasites themselves rather than by their host, although the host, in each case, is always responsible for the initiation of the sexual process as well as for carrying it to completion.

Notes: SUMMARY. A small soil amoeba was purified by an agar-surface migration method. The amoeba was grown axenicly in a liquid medium composed of 1% proteose peptone, 1% glucose, and inorganic salts. The amoeba was identified as a species of Acanthamoeba. A hypothesis on the mechanism of agar-surface purification of amoebæ is proposed. The nutritional requirements of this isolate are discussed; it is concluded that this organism metabolizes glucose.

Notes: SUMMARY. An electron microscope study of thin sections of duck erythrocytes infected with Plasmodium lophurae revealed that the so-called “residual body” is a food vacuole formed by invagination from the cytoplasm of the host cell. Several such food vacuoles may exist in a single parasite. Digestion of hemoglobin evidently proceeds only within these food vacuoles, since they are the only place in the parasite where the characteristic malarial pigment granules may be found. This finding changes the role ascribed to the residual body and gives a new concept of the feeding mechanisms in P. lophurae and other malaria parasites. The cytoplasm of the host is taken in by the parasite by phagotrophy and not only as previously assumed, by diffusion.The fine structure of P. lophurae shows all major components found in other protozoan and metazoan cells. Some of the organelles appear to have a much simpler structure connected probably with the highly specialized intracellular parasitic life.

Notes: SUMMARY. Transfers of Euglena gracilis to fresh media gave rise to increased volumes of the flagellates, the magnitude of expansion varying with temperature, pH, osmotic pressure, and number of nutritional particles in the medium. Expansion was accompanied by decreased protoplasmic density and increased intracellular solids and water. When the population density of the flagellates was more than optimal, competition for substrates was reflected in reduced maximum volume. Below the optimal range, a similar decrease in maximum volume was observed.

Notes: SUMMARY. A ciliate found in the renal organ of the gray garden slug, Deroceras reticulatum, is referred to Tetrahymena (Paraglaucoma) rostrata (Kahl). In the parasitic phase, the ciliate is evidently not histiophagic. It is readily cultivated in bacterized tissue infusions, and has been established in axenic culture in yeast extract.The number of complete primary ciliary meridians in ciliates of the parasitic phase has been observed to range from 41 to 58; in ciliates from cultures, the number of meridians has been observed to range from 28 to 37. In culture, the form of T. rostrata from D. reticulatum appears to be morphologically identical with a strain (NZ-4) recovered from soil in New Zealand.

Notes: SUMMARY. In a survey of 52 rodents of 25 species from Grand Canyon National Park, Arizona and its vicinity, the following species of Eimeria are described: E. tamiasciuri n. sp. from the red or spruce squirrel, Tamiasciurus hudsonicus; E. lateralis n. sp. and Eimeria sp. from the mantled ground squirrel, Citellus lateralis; E. eutamiae n. sp. from the cliff chipmunk, Eutamias dorsalis; E. thomomysis n. sp. from the pocket gopher, Thomomys bottae; E. perognathi n. sp. from the rock pocket mouse, Perognathus intermedius; E. albigulae n. sp. from the white-throated woodrat, Neotoma albigula; E. operculata n. sp. from Stephens' woodrat, Neotoma stephensi; E. peromysci n. sp. and E. arizonensis n. sp. from the piñon mouse, Peromyscus truei; E. eremici n. sp. from the cactus mouse, Peromyscus eremicus; and E. onychomysis n. sp. from the northern grasshopper mouse, Onychomys leucogaster.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Notes: SUMMARY. A comparative cytological study of the buccal organelles in seven species of Paramecium and a critical analysis of their morphogenesis during binary fission are presented. The. results show several heretofore overlooked features of the buccal system which may possess considerable systematic significance. On the basis of the morphology of the buccal apparatus and its mode of stomatogenesis, the genus Paramecium, traditionally placed among the trichostomes, is considered to be a true member of the order Hymenostomatida. The taxonomic utility of the buccal organelles and their phylogenetic implications are discussed in the light of the fundamental principles underlying the “new systematics” of ciliated protozoa.

Notes: SUMMARY. In ciliates belonging to the two gymnostome families Chlamydodontidae and Dysteriidae as well as to the order Chonotrichida the macronucleus is composed of two parts which are distinct but in very close juxtaposition. One part, here called “orthomerous,” contains granules or microsomes of desoxyribonucleoprotein and several nucleoli; it thus shows the normal structure of a macronucleus of the ordinary type. The other part, “paramerous,” contains desoxy-ribonucleic acid diffused, apparently, throughout a homogeneous karyolymph and possesses, in addition, several nucleoli and an endosome of desoxyribonucleoprotein.The three groups of ciliates under discussion are closely related and constitute an assemblage of forms remarkably evolved. The “heteromerous” structure of their macronuclei must be considered as a secondary acquisition and a differentiation of the “homeomerous” type which characterizes the structure of the macronucleus in most other ciliates.

Notes: SUMMARY. Strains of Chilomonas paramecium differing in degree of resistance to sulfanilamide have been established through acclimatization to this sulfonamide at 50, 100 and 200 mg. %. Resistant strains differ from the normal stock in their enhanced sensitivity to p-aminobenzoic acid. In the normal stock, sulfanilamide inhibition is reversed at an SA/PABA ratio of 10,000 but not at 20,000; in the least resistant strain, at a ratio of 400,000 but not at 800,000. In resistant strains inhibition is reversed by folk acid, methionine, adenine, cytosine and thymine; in the normal stock, none of these metabolites produces reversal. In high concentrations of PABA (10–20 mg. %) growth of the normal stock is only retarded, whereas the strain least resistant to sulfanilamide fails to recover from exposure to 20 mg. % PABA. The strain most resistant to sulfanilamide is most susceptible to PABA in high concentrations. The data suggest that resistance to sulfanilamide in C. paramecium may depend mainly upon an accelerated synthesis of PABA.

Notes: SUMMARY. Paramecium caudatum exposed to 120 lbs./in.2 (gsi) gauge pressure (g.p.) at 27°C. died in 2 hours 32 ± 15 minutes. Under similar conditions with the addition of 0.04 m pyruvate and 8 × 10-3 m Mg++ they lived at least twice as long. Substitution of Co++ or Mn++ for Mg++ provided slightly less protection.Addition of sulfhydryl (SH) reagents to paramecia exposed for 2 hours to 120 psi (g.p.) oxygen resulted in reversal of oxygen poisoning. By means of these reagents oxygen poisoning could be reversed indefinitely. It now appears that direct evidence has been obtained to show that oxygen poisoning is a result of SH inactivation. The extent of the poisoning depends upon the rate of oxidation of SH groups by the oxygen as opposed to the rate at which the organism can reduce oxidized and/or furnish new SH groups.

Notes: SUMMARY. Objectives of the investigation were to: (1) ascertain whether, on the basis of enzyme inhibition, localization, and staining intensity, multiple phosphatases exist in Tetrahymena pyriformis W; (2) show activity values for phosphatase in specimens of T. pyriformis W from various ages and types of culture solutions; and (3) test the reliability of the Ca-cobalt technique for demonstration of phosphatase in cell nuclei.Complete inhibition of phosphatases (Ca-cobalt) was obtained with semi-carbazide, HCI and 0.2 m citrate buffer, pH 5.5. Potassium cyanide (0.01 m) tended to activate phosphatase with adenosinetriphosphate and inhibited phosphatase with Na-glycerophosphate, adenosine-5-phosphate, adenosine-3-phosphate, glucose-1-phosphate, and creatine phosphate solutions. A differential inhibition of phosphatase was obtained with inhibitors other than KCN.Phosphatase-active areas were in essentially the same intracellular position in all substrate solutions with the exception of enzyme-active areas in organisms from tryptone-MgCl2-citrate (0.01 m, pH 5.5) solutions; in the latter, both nuclear and cytoplasmic activity was evident. Organisms from tryptone-MgCl2-citratel (0.02 m), and vitamin-enriched tryptone solutions exhibited abundant cytoplasmic phosphatase with the azo-dye procedure. On the other hand, cytoplasmic phosphatase was not demonstrated with the Ca-cobalt procedure.Results obtained with enzyme inhibitors, various substrate solutions and evaluation of staining intensities suggest but do not demonstrate that 3 phosphomonoesterases, which hydrolyze glycero-phosphate, adenosine-5-phosphate, and adenosinetriphosphate, exist in Tetrahymena pyriformis W.Nuclear reactions obtained with the Ca-cobalt procedure were believed to be artifacts, with the exception of reactions obtained with cells from tryptone-MgCl2-citrate solutions subsequent to incubation in adenosinetriphosphate solution.

Notes: SUMMARY. The acetate metabolism of Euglena grown on ethanol at pH 3.5 (Et-grown) differs from that of the same strain grown on acetate at pH 7.3 (Ac-grown) in several respects. Et-grown cells have a rate of acetate oxidation at pH 7.0 lower than that of Ac-grown cells. The rate of acetate oxidation by Et-grown cells is markedly increased at low pH, whereas that of Ac-grown cells is relatively independent of pH. At pH 5.5, the respiratory rate of Et-grown cells can be increased by increasing acetate concentrations up to 18.4 IBM, whereas that of Ac-grown cells is independent of acetate concentration above 4 mM. At pH 7.0, both types of cell are unaffected by changes in acetate concentration above 4 mM.Et-grown cells incubated in the presence of acetate for about 80 minutes frequently adapt to acetate, taking on characteristics similar to those of Ac-grown cells.

Notes: SUMMARY. Genetic cross transfer of laboratory-induced drug resistance from a tryparsamide-resistant strain to a sodium naphuride-resistant strain and vice versa has been tested in cultures of Trypanosoma gambiense. The results obtained from a variety of different concentrations of the two drugs used do not give any indication of sexuality in these flagellates.

Notes: SUMMARY. The metabolism of Tritrichomonas foetus (strain, BP-1) and trichomonads from the nasal cavity and cecum of swine was studied manometrically under similar experimental conditions. At pH 6.4, quantitative and qualitative differences were observed. The cecal (probably T. suis) and nasal trichomonad used glucose, galactose, fructose, mannose, lactose, sucrose, raffinose, and trehalose. T. foetus used all except lactose and raffinose. All three were inhibited by iodoacetate and arsenite. T. foetus and the nasal form were significantly inhibited by fluoride and 8-hydroxyquinoline, whereas the cecal trichomonad was not. At varied pH, all failed to oxidize Krebs' cycle intermediates. The amounts of oxygen consumed by T. foetus and the nasal trichomonad in the presence of lactate and pyruvate were at levels similar to those with disaccharides; the cecal trichomonad was indifferent toward both substances. Anaerobically, lactate and pyruvate increased the evolution of gas by all three trichomonads. Aerobic acid formation was demonstrated for all three forms. Anaerobically, metabolic CO2 and gas(es) that were not absorbed by KOH were evolved by all three. Pure oxygen was inhibitory to glucose utilization and stimulatory to the endogenous respiration of all trichomonads; the nasal form was affected the least.The writer believes that the cecal trichomonad is different from T. foetus and the nasal trichomonad of swine. The relationship between the nasal trichomonad and T. foetus remains in doubt.

Notes: SUMMARY. Haemoproteus columbae of English wood pigeons (Columba palumbus palumbus L.) was found to undergo sporogony in Ornithomyia avicularia. It is suggested that this insect is a vector of H. columbae, in spite of the failure of six attempts to transmit the haemosporidian to uninfected domestic pigeons (C. livia var. domestica) by the bite, or injection, of infected O. avicularia.

Notes: SUMMARY. After removal of nucleic acids, by enzymatic digestion and dialysis, from an unidentified component of the medium, it was possible to show specific purine and pyrimidine requirements for Paramecium multimicronudeatum. The purine requirement was satisfied by guanosine, deoxyguanosine, guanylic acid or deoxyguanylic acid, but not by any of the adenine derivatives. Cytidine, deoxycytidine, cytidylic acid, deoxycytidylic, uridine, uridylic acid or deoxyuridine would serve as the pyrimidine source, whereas thymidine and thymine would not. The free bases guanine, cytosine and uracil did not replace their respective pentose derivatives. Of the active compounds, the pentonucleosides were more active than the pentonucleotides. Inbsine, xanthine, 2,6-diamino-purine, 5-methylcytosine, and orotic acid did not support growth.

Notes: SUMMARY. The pattern of mating type distribution observed at conjugation under different conditions in stock 51, variety 4, of Paramecium aurelia is presented. When the two mating types (VII and VIII) found in this variety are crossed, each pair member usually gives rise to two caryonides of its own mating type. Either parent may, however, give rise to progeny unlike itself. When cytoplasmic fusion is induced by antiserum treatment, the two members of a pair characteristically yield progeny of the same mating type, and the progeny are usually mating type VIII. The direction of change can be influenced to some extent by the temperature at which conjugation occurs; changes from VII to VIII are more frequent at the higher temperatures.A modification of mating type distribution is observed when conjugation occurs in the unstable clones designated as “selfing caryonides”. Changes are frequent under these circumstances, but are predominantly from type VIII to type VII—precisely the reverse direction observed when pure clones are crossed. The relative frequencies of the changes in the two directions are again influenced by the temperature at which conjugation occurs. These observations indicate a separation of two normally correlated macronuclear functions—the activity in determining the phenotype (mating type) of the cell and the activity in determining the cytoplasmic conditions responsible for nuclear differentiation in the following generation. An interpretation of these results, based on macronuclear heterogeneity, is suggested.

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

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

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