ALBERT

Notes: SYNOPSIS. Two main kinds of morphogenetic events occur among protozoa: (1) reproduction; (2) processes of reorganization, including encystment, excystment, sexual processes, structural and physiological adaptations exhibited in the course of complex life cycles, and restorative events elicited by environmental stimuli. Examples of such events are discussed with reference both to their own intrinsic interest and to their value in the study of cellular differentiation in general. Stomatogenesis in ciliates provides a remarkable instance of extensive and rapid differentiation. The phenomenon may be studied to advantage not only in reproduction but also in the macrostome-microstome transformation. Other simple transformations in protozoa providing unparalleled material for experiments on cytodifferentiation under controlled conditions are excystment and encystment, the amebo-flagellate transformation, and the leishmania-leptomonad change. The more complex transformations occurring in the life cycles of trypanosomes and in the appearance of sex under the influence of an insect hormone provide additional material of basic significance to an understanding of differentiation.

Notes: SYNOPSIS. Euglena gracilis strain Z rendered permanently apochlorotic by several chemical and physical agents contains bodies similar in size to normal plastids. Some of these bodies contain lamella-like structures; others contain crista-like structures. The lamella- and crista-like structures are made up of 2 electron-dense layers separated by an electron-lucent layer.These structures are compared to normal lamellae and it is suggested that apochlorotic cells contain lamellae that lack the thicker, inner electron-dense layer, or more likely, that the apochlorotic condition prevents two discs from fusing to produce the thicker inner electron-dense layer which contains the photosynthetic pigments.

Notes: SYNOPSIS. Cell-free extracts of Tetrahymena contain adenase, guanase, xanthine oxidase, uricase, and adenosine deaminase. The levels of activity of the latter three are of the same order of magnitude as in mammalian tissues. 5′-Adenylic acid deaminase is also present in ciliate extracts. Spectrophotometric assays of this enzyme indicate formation of two intermediates which, although not as yet identified, are not precursors of uric acid, the expected product of deamination of the nucleotide.

Notes: SYNOPSIS. A study of the ectoplasm and infraciliature of Spirostomum ambiguum has been made with light and electron microscopy. Proceeding from the exterior, the cortex is described as the highly structured ectoplasmic portion of Spirostomum consisting of ectoplasmic ridge components and ectoplasmic furrow components. The pellicle invests the ectoplasmic ridges, ectoplasmic furrows, cilia, and adoral membranelles. Electron micrographs show that the cell surface is bounded by two membranes, for the most part parallel. The outer one is continuous with the unit membrane of each cilium; the course of the inner membrane has not been determined in areas bearing cilia.The ridge components are: (i) a collection of fibrils called peripheral ectomyonemes, situated beneath the inner membrane of the cell surface, oriented parallel with the organism's longitudinal axis and following the peripheral contours of each ridge; (ii) distinct rows of tubular fibrils which form a longitudinal bundle called lateral ectomyonemes, situated in the lower portion of each ridge and oriented parallel to its spiral course; (iii) cytoplasmic matrix suspending and surrounding components (i) and (ii). Mitochondria and unidentified electron-opaque oval-shaped or round bodies called X-bodies are dispersed in the ectoplasmic ridges but they also occur in the endoplasm; therefore, they are considered to be transient inclusions instead of constituents of the ridges.The furrow components are: (i) the body cilia and adoral membranelles; (ii) the kinetosomes; (iii) root fibrils, called kinetodesmal strands, of the adoral membranelles; (iv) cytoplasmic matrix suspending and surrounding the furrow components.A trabecular band of randomly oriented filaments, called the endomyoneme is described as possibly the structure called M-band by Randall and Jackson, 1958, and contractile fibrillar system by Yagiu and Shigenaka, 1963.It is suggested that collections of distinct fibrils in Spirostomum be called fibrillar complexes. Acceptance of this suggestion will lead to the designation of four distinct fibrillar complexes in heterotrichs; all four complexes have been described or mentioned in previous studies.Some findings of previous investigators are discussed and confirmed (especially pertaining to Randall and Jackson, also Yagiu and Shigenaka, cited above). Inferences from these independently derived findings are discussed.

Notes: At the age of 50 a Puka-Pukan retires from manual labor and becomes one of the members of The Company, spending hi; evenings shooting popguns or playing checkers, and his nights in ordering the young fry about. He never again has to go fishing, to gather coconuts, or to do any other work.When the malos [young men] bring in their fish they are given to the fathers, who divide them after picking out the choice bits for themselves… To be sure, many of the fathers spend a day or two at fishing now and then, but this is not required of them and they do it only to pass the time… (22).

Notes: SYNOPSIS. The subcellar components within living inter-phase Amoeba proteus organisms were stratified by centrifugal forces which ranged from 700 g to 10,000 g. The amoebae were fixed in OsO4 immediately afterwards, embedded in Epon resin, and examined with an RCA EMU-3E or an RCA EMU-3F electron microscope. For convenience in presentation, the strata are classified into 8 zones and discussed in order from the centripetal (zone 1) to the centrifugal pole. Zone 1 contains the fat globules most of which range in size from 1 to 5 μ; the centrifuged globules do not coalesce, probably because each globule has a surrounding membrane. Zone 2 has the contractile vacuole, groundplasm, and some irregular vacuoles which are a few microns in size. Zone 3 is the largest in volume and contains mostly groundplasm in which are suspended numerous small vesicles (ca. 0.5 μ or less). Many of these are about 0.3 μ in size and appear to be the alpha granules previously described by light microscopists as minute particles (ca. 0.25 μ), and also studied by us with the phase microscope in living, centrifuged amoebae. In addition, this zone contains electron-dense prolate spheroid bodies which are oriented in the direction of the centrifugal force. Zone 4, which is not sharply separated from zones 3 and 5, contains a variety of vesicles and vacuoles ranging from 0.1 μ to a few microns in diameter, and scattered electron-dense spheroidal bodies, all suspended in groundplasm. Zone 5 contains the nucleus and a well defined stratum of Golgi bodies. Zone 6 is the mitochondrial stratum with quite distinct borders while zone 7 has the food vacuoles and the infective organisms. Zone 8 is made up of membranous vacuoles containing crystals. In amoebae centrifuged at 10,000 g the spaces between the crystal vacuoles have a high concentration of 40-mμ electron-dense particles that frequently appear in small aggregates. Some components, such as the small vesicles and the electron-dense prolate spheroid bodies characteristic of zone 3, do not form a sharply defined stratum even at forces of 10,000 g. A comparative electron microscope study is made between centrifuged A. proteus and Pelomyxa illinoisensis amoebae, the latter being relatively radiosensitive.

Notes: SYNOPSIS. Studies of certain members of the order Peritrichida, namely species of Carchesium, Epistylis, Vorticella and Zoothamnium, have revealed prominent argentophilic granules, probably cuticular pores, on the bells of all species, located on the transverse striations which encircle the bells. With light microscopy they appear similar to the basal bodies or kinetosomes found in the peristomal regions of the sessile forms, in the posterior ciliary girdles of the telotrochs, and in the scopulas of both sessile and motile organisms. Telotrochs of the various species are depicted with single and multiple rows of the basal bodies from which the membranelles of the locomotor girdles arise.

Notes: SYNOPSIS. A classification of the phylum Protozoa at supra-familial levels is given with definitions or descriptions of all of the involved taxa, some 140 in number. The scheme represents the result of the cooperative efforts of an international group of specialists and consultants who have‘been studying the overall problem for the past several years. Innovations of a nomenclatural nature have been held to a minimum, aside from the use of a system of uniform endings, but several major shifts of taxonomic significance have been introduced at all levels treated, including the subphyla. These revisions are explained in appropriately placed footnotes.

Notes: SYNOPSIS. A comparison has been made of the characteristics of proteins present in two strains of Amoeba proteus, Amoeba discoides, and Chaos chaos. Extractable protein mixtures of each of the strains have been compared with respect to electrophoretic mobilities, enzyme activities, and immunological reactivities. With one slight exception, the three Amoeba strains appear to be identical by all the tests that have been performed but each of the three strains is dearly different from C. chaos by the same tests. The exception may be a difference of a single immunologically active component between A. discoides and one of the A. proteus strains, according to a preliminary observation.

Notes: SYNOPSIS. Active, normal sera or other body fluids from many vertebrate species were found to cytolyze Tritrichomonas augusta; heat inactivated sera agglutinated the organisms. Techniques were devised for quantitative determination of “natural” agglutinating and lytic activity against a number of trichomonads. Amphibian, avian, mammalian, and reptilian sera all possessed activity, as did chicken egg yolk, or yolk sac contents, human ascitic fluid, and cow's milk. For individuals of a given species, levels of “natural” agglutinin did not vary significantly. Among donor species, there were wide and consistent differences. The serum of any one individual, tested against 6 strains of T. augusta, showed constant activity. Agglutinating activity was relatively unaffected by changes of physical factors in the reaction milieu. Lytic activity was restored to heat-inactivated serum by addition of guinea pig serum as a source of complement. When serum was fractionated, agglutinating activity was found primarily in the γ globulins and on into the β. On the basis of these reactions and the activity of specific serum fractions, an antibody mechanism has been postulated.By means of reciprocal agglutination tests with absorbed sera, both “natural” and immune agglutinins have been shown to be specific for Tritrichomonas augusta, T. foetus, and T. suis (?), as well as for Trickomonas gallinarum and Trichomonas vaginalis. Absorption with one species does not remove activity against others. Among strains of T. augusta, absorption with any one removes some antibody against others, but not necessarily all. On the basis of reciprocal absorption and test of 6 strains, 3 antigenic groups have been established: 2 groups are well-separated; the 3rd intermediate between the others and cross-reacting with both.Lack of agglutinin absorption by 2 common enterobacteria, a yeast, and Forssman antigen (sheep erythrocytes) showed that these, at least, were not involved as sources of heterophil stimulation for “natural” antibody. Whether “natural” antibody results from heterophil stimulation, however, or is genetically determined, has not been answered. Direct stimulation of “natural” antibody production by occult infection with trichomonads could not have occurred in the case of trichomonad-free, laboratory reared chicks, or mammalian sera active against T. augusta.

Notes: SYNOPSIS. Two experiments attempted to produce passive immunity against Eimeria bovis coccidiosis in Holstein-Friesian calves. Immune serum concentrated by a freezing technique, or serum globulin obtained by a precipitating technique from immune calves, was injected intravenously or intraperitoneally into young calves. Four calves received concentrated immune serum injected intravenously on the day of oral inoculation with sporulated oocysts and again 7 and 14 days later. Four calves were given intravenous injections with some of the same serum on the 7th and 14th days after inoculation and 4 others were given a single similar injection with the same serum 14 days after inoculation.Three calves in a second experiment received intraperitoneal injections of serum globulins in increasing amounts every 3 days for 2 weeks. The calves were then orally inoculated with sporulated oocysts one week after the last globulin injection. Some calves receiving immune serum had an anaphylactoid reaction characterized by increased respiration rate, dyspnea, coughing, and salivation; however, all affected calves recovered spontaneously within 2 hours. Calves receiving serum globulin had no reactions.Coccidiosis developed in all of the calves in spite of the injection of immune serum or globulin presumed to carry the immune factor. There was no detectable difference in the rate of oocyst discharge or in clinical symptoms between treated and control calves; therefore, no evidence of passive immunity was observed.

Notes: SYNOPSIS. A rapid and sensitive method for determining the nutritional requirements of marine phytoflagellates in axenic culture is described. C14 assimilation (added as NaHC14O3) was used as a measure of response to minimal concentrations of nutrients and for studying the effects of osmotic changes on cells. The results demonstrated that Glenodinium halli Freudenthal & Lee required B12, was stimulated by thiamine, and that it is a euryhaline species. The applications and advantages of this technique in nutritional studies and bioassays are discussed.

Notes: SYNOPSIS. Factors influencing the cultivation of entodinia in vitro have been studied. It was found that removal of particulate material, culture division, or a combination of both resulted in similar maximum protozoal concentrations. At the same time, untreated culture concentrations declined rapidly after reaching a maximum concentration at about the tenth day.At concentrations of streptomycin greater than 25 μg per ml of media, increasing the level of streptomycin extended the time required for a culture to attain a maximum protozoal concentration. A significant relationship (P〉.01) was demonstrated between the starch concentration and the protozoal concentration, and it was found that various combinations of starch and streptomycin produced different relative protozoal concentrations in initial and established cultures. Implications arising from these results are discussed.

Notes: SYNOPSIS. Cultures of Chlamydomonas moewusii begun with log-phase cells of any age had the same lag phases and showed slight but demonstrable synchronous division. Those begun with stationary-phase cells had longer lag phases and showed pronounced synchronously reproductive tendencies. Cultures grown under favorable or unfavorable conditions, and their log-phase cells compared, behaved like log- and stationary-phase cells respectively. Both stationary phase and unfavorably grown cultures shared some of the characteristics of cultures synchronized by light-dark cycling. A light-dark cycled population divides synchronously in direct response to the cycle, and not as a result of being transferred from one medium to another. Synchronous division will occur as 8-fold increases with initial cell densities as low as 10 cells/ml and as high as 100,000 cells/ml. Initial concentrations above 100,000/ml will result in synchronous bursts of less than 8 times the cell number. Cycled cells will continue to divide synchronously when exposed to continuous illumination for an additional 24 hr (i.e., 1 entire “cycle” period). After 12 more hr, they divide exponentially. Continuously illuminated young log cells when subjected to a light-dark regimen begin growing and dividing synchronously by the end of the 1st 12-hr dark period (i.e., during the 2nd 24-hr cycle). The synchronized cell cycle is described cytologkally and quantitatively, and the degree of synchrony for each of the phases of the cell cycle analyzed. After comparing the data from the synchronously and randomly growing cultures, an hypothesis is suggested to explain exponential and synchronous growth and division.

Notes: SYNOPSIS. Evidence is presented for killer and sensitive animals in Paramecium polycaryum. The killer animals excreted in the culture medium a lethal substance which killed the sensitive animals. The lethal substance was unstable at high temperatures and was completely precipitated by centrifugation at 10,000 rpm for 30 minutes. Comparative immunity to killing by killer animals was shown to be possessed by some animals of certain sensitive stocks.Attempts to find a cytoplasmic particle comparable to “kappa” in P. aurelia in killer animals were not successful.

Notes: SYNOPSIS. Sulfate-S35 uptake by intact Euglena cells, as well as incorporation of sulfate-S35 into the insoluble fractions of the cells, was partially inhibited by adding iodoacetamide simultaneously or ten minutes before radioactive sulfate. The identification of S-cysteine acetamide and S-glutathione acetamide showed the presence of glutathione and cysteine in the soluble pool of Euglena but methionine, homocysteine, and S-adenosylmethionine were not found during these experiments. An unidentified radioactive peak was eluted by 2 n HCl during column chromatography of the soluble fraction of Euglena cells. The major compound in this peak was identified as L-cystine on the basis of its infra-red spectrum, paper and column chromatographic characteristics and optical rotation. The use of iodoacetamide permitted the independent demonstration of cysteine and cystine in the soluble pools by eliminating oxidation artifacts.

Notes: SYNOPSIS. Leishmania tarentolae requires at least 10 mμg riboflavin per ml for optimal growth on successive subculture in a denned medium. At this level many organisms are aflagellate or with a short flagellum; higher concentrations of riboflavin did not increase the yield of leptomonads but did increase the proportion with a flagellum at least as long as the body. At limiting levels of riboflavin, acriflavin markedly inhibited growth without producing akinetoplastic forms. With riboflavin at 20 mμ/ml or higher, acriflavin at around 500 mμg/ml permitted an approximately 10-fold multiplication. Seventy % of the leptomonads formed were akinetoplastic and they could not give rise to subcultures.In electron micrographs of acriflavin-treated organisms the nucleus was unaffected but the cytoplasmic organelles, notably the kinetoplast and mitochondria, were altered. The mitochondria appeared swollen with their cristae replaced by circular profiles. In the kinetoplast the dense fibrillar material (probably DNA) lost its structure, became diffuse, and eventually disappeared. The observed changes again indicate close relationship between the kinetoplast and the mitochondria of hemoflagellates.

Notes: SYNOPSIS. Trypanosoma conorhini has been isolated from infected Triatoma rubrofasciata in Singapore. Parasites derived from the triatomid gut were inoculated into NNN medium and some cultures maintained at 25° to 27°C while others were kept at 37°. In cultures kept at lower temperatures crithidial forms predominated; however, at 37° blood-stream trypanosome forms developed and survived for 10 days or more.

Notes: SYNOPSIS. Sporocysts of P. crystalligera readily germinate to permit escape of their sporozoites when placed in an infusion of the contents and the tissue of the midgut of the beetle host, Dermestes vulpinus. To determine the type of digestive enzyme required for germination to take place, sporocysts were exposed in hanging drops to 0.25% (w/v) concentrations of commercial preparations of trypsin and lipase in a saline solution. Sodium taurocholate was used in combination with certain of the enzyme preparations.Up to 99% of the sporocysts exposed to trypsin 1:300 and to a relatively crude preparation of lipase (containing some trypsin) germinated within three hours. A refined preparation of trypsin (2 × crystallized, salt-free) induced up to 65% of the sporocysts to germinate within three hours. Refined lipase (50μl CO2/mg/30 min.) had no germinating effect upon sporocysts, either by itself or in combination with sodium taurocholate. In mixtures, crystallized trypsin seemed definitely to be inhibited by sodium taurocholate, and perhaps was inhibited also by refined lipase.The fact that trypsin is effective in causing germination to take place suggests that the germination of sporocysts in the digestive tract of D. vulpinus depends upon a proteolytic enzyme. Unlike trypsin, which was more active in solutions adjusted to an initial pH of 7.0 and 8.0 (especially the latter, in the case of crystallized trypsin) than in those of pH 6.0, this enzyme was more effective in inducing germination at pH values of 6.0 and 7.0.

Notes: SYNOPSIS. Two blood trypanosome antigens (PR and AG) have been isolated from the serum of infected rats. These antigens are specific for each strain of trypanosome. The AG antigens, detected by agar diffusion techniques, have been extensively purified and are prctein in nature. Those isolated from two different strains differ in their heat sensitivity and in their elution patterns from calcium phosphate gel. The AG antigens are apparently not involved in the protection of mice after immunization with infected rat serum. The PR antigens, not yet detected by agar diffusion techniques, protect mice after immunization. These antigens also appear to be proteins.At least two antigens in the soluble portion of blood trypanosome homogenates are common to the “brucei” group of trypanosomes. These antigens are not involved in determining the serotype of different strains of trypanosomes. Furthermore, there are no biological properties by which the common antigen can at present be characterized.The enzyme hexokinase has also been found to be antigenically similar in both blood and culture trypanosomes. This enzyme, however, has not been detected by agar diffusion techniques. This, therefore, suggested that there are probably numerous antigens common to different strains of T. rhodesiense which have not been detected by this technique.

Notes: SYNOPSIS. In continued observations on the in vitro growth and multiplication of the bloodstream trypanosome stage of Trypanosoma conorhini, a better medium was found for cultivating these forms at 37°C, but no subcultures could be obtained. The infectivity for mice of the blood type trypanosomes grown in vitro was comparable to that of the metacyclic trypanosomes. The only reproducing forms of T. conorhini found in the vertebrate were in the trypanosome stage.It was also found that the in vitro reversion of the bloodstream trypanosome into crithidia, such as occurs in the invertebrate host and in the usual diphasic culture medium, is dependent on at least two factors: if incubated at 25–28° reversion did not occur in any of the liquid media tried (all containing blood serum and hematin or hemoglobin), unless total blood was part of the inoculum or washed red blood cells were added to the media; on the other hand, no reversion was seen, even in the presence of red blood cells if the cultures were incubated at 37°.

Notes: SYNOPSIS. Alkaline (pH 8.4) and acid (pH 5.4) phospha-tases were demonstrated in the cytoplasm of culture forms of Trypanosoma ranarum by the naphthol-AS methods. The enzymes were in both slender and pear-shaped flagellates, and variaticn of incubation temperature (10°, 31° and room temperature) did not adversely influence the appearance of the chromogenic granules. Enzyme determinations by sulfide methods indicated that alkaline phosphatase was concentrated in the nuclear area. Acid phosphatase could not be found by this method.

Notes: SYNOPSIS. A polymorphic allogromiid (our strain NF) was isolated in monoxenic culture but attempts at its axenic culture failed. Growth of monoxenic cultures was stimulated by various metals and vitamins. The morphology and life cycle of this allogromiid with a prominent collar have been studied in detail. It varied in form from ovoid to elongate bioral “Shepheardella-like” forms and to irregular polyoral organisms. The organisms ranged in length from 56–385 μ (118 μ± 50.54) and in width from 35–385 μ (99 μ± 39.34). The number of nuclei per organism averaged 8.9 ± 6.3 (range 1–40). Reproduction of “Shepheardella-like” forms was by binary fission. Three types of budding have been observed and, rarely, schizogony. No evidence for sexual reproduction has thus far been seen.

Notes: SYNOPSIS. A nonpathogenic histomonad, morphologically identical to that found in pheasants by Wenrich in 1943, is described as Histomonas wenrichi n. sp. Its dimensions are about 1.5 × those of H. meleagridis. It has 4 flagella instead of the 1 or 2 that characterize the latter species. It does not multiply in the host tissues nor produce visible responses to its presence there, and it does not exist as the clear “tissue form” that is common in active H. meleagridis infections. Histomonas wenrichi n. sp. can be transmitted to turkeys, chickens, and pheasants by either rectal inoculation or by feeding embryonated eggs of Heterakis gallinarum grown in birds harboring the nonpathogenic histomonad in the ceca. Usually fewer than half the female heterakids so grown produce eggs capable of transmitting this histomonad, and a total of 200 to several thousand eggs from worms recovered from Histomonas-infected birds may be required to produce one Histomonas infection. Histomonas wenrichi n. sp. has been propagated in more than 2000 chickens and turkeys over an 8-year period, during which time it has been transmitted by 18 generations of Heterakis. It has frequently been grown in birds in which H. meleagridis was also present, and upon reisolation it maintained all of its original characteristics. It has not yet been cultivated in vitro.

Notes: SYNOPSIS. Of 6 representative antibiotics only tetracycline inhibits this phytoflagellate. Whereas penicillin, neomycin, erythromycin and streptomycin exert no real influence on the organism, addition of chloramphenicol to the growth medium results in a marked increase in cell yields.

Notes: SYNOPSIS. The occurrence of monstrous individuals of Dileptus is reported. These monsters appeared in cultures which had been fed planarians for over 72 hr. The first abnormal forms to appear were giants, 700–1200 μ long, which were common in the cultures after 72 hr. Giants were occasionally observed to develop a large, non-contractile vacuole in the central region of the body after a week of feeding on planarians. A sequence of events is described in which this vacuole enlarged until the animal appeared to be a water-filled sphere which then collapsed into an amorphous blob. This blob then divided unevenly to produce as many as seven small Dileptus. The described morphological changes are presumed to be a result of Dileptus' feeding on planarians. The similarities between abnormal Dileptus and monstrous individuals of other species are discussed.

Notes: SYNOPSIS. Genomic exclusion is an aberration that occurs during conjugation in variety 1 of Tetrahymena pyriformis. Instead of containing markers from both parents, the out cross pairs are either homozygous for all the genes of one parent (unilateral genomic exclusion); or, some of the pairs are homozygous for the genes of one parent and other pairs are homozygous for the genes of the other parent (bilateral genomic exclusion). This phenomenon was first demonstrated in the C strain: some stocks evoke unilateral genomic exclusion; others, bilateral genomic exclusion. C*, inbred for 5 generations, was used to explore this phenomenon in some detail since unilateral genomic exclusion of C genes occurs in almost all pairs in outcrosses of C*. In a mating of C*, both exconjugants are recovered, both are dipioid and similar in phenotype. Using morphological markers, C* can be shown to participate in the mating; therefore, C* does not induce illegitimate matings of the normal mate. When the normal mate is heterozygous for alleles (HA/HD) not present in C*, 3 classes of offspring (HA/HA, HA/HD and HD/HD) are produced in a 1:2:1 ratio. These observations indicate that 2 meiotic products of the normal mate unite to form the syn carya. The genetic ratios obtained in 1 and 2 factor crosses limit the possible cytogenetic bases for genomic exclusion. They suggest that 1 of the 4 haploid nuclei replicates and the replica fuses randomly with any 1 of the 4 nuclei. The 2 schemes of nuclear behavior (single fertilization, double fertilization) that would satisfy these requirements have not yet been resolved.

Notes: SYNOPSIS. In defined media growth inhibition of the flagellates Ochromonas danica and Euglena gracilis, the photosyn thetic bacterium Rhodopseudomonas palustris, and Coryne bacterium bovis was overcome for each organism, for concentrations of 4-nitroquinoline N-oxide (4-NQO) to ca. 5 μg/ml, by a combination of L-tryptophan, riboflavin, nicotinic acid, L-tyrosine, and less sharply, thymine and naphtho quinones. Tryptophan used alone was effective only in rather high concentrations—ca. 0.2 mg/ml for 4-NQO 2 μg/ml; it was competitive with 4-NQO through this range. At least for Euglena, gramine and 5-methyl-DL-tryptophan were about as effective. 4-NQO uptake may therefore be via the trypto phan transport system. 4-NQO may be a uniquely stable, accessible counterpart of the more polar, more carcinogenic compounds into which mammals oxidatively convert the azodye carcinogens by N-hydroxylation and the hydrocarbon carcinogens by hydroxylation and ketonization.

Notes: SYNOPSIS. When the antibiotic L-azaserine was injected intraperitoneally into female Ha/ICR albino mice infected with T. equiperdum, a marked but temporary inhibition of trypanosomal reproduction was observed and survival time of the hosts was more than doubled. The efficacy cf a given dose of azaserine was considerably reduced when its equivalent was divided equally over a 5-day period. Azaserine was much more effective when injected intraperitoneally than when given by gastric intubation, even though measures were taken in the latter circumstance to reduce the rate of degradation of the drug by gastric juice and the liver. Some purine analogs were tested in combination with azaserine for ability to prolong the lives of mice infected with T. equiperdum; 6-mercaptopurine was the only one that significantly enhanced the efficacy of azaserine. Evidence is presented that azaserine inhibits trypanosomal reproduction directly rather than by a host-mediated mechanism.

Notes: SYNOPSIS. Haemoproteus sp. (probably a subspecies of H., columbae Kruse, 1890) of Columba p. palumbus L. in England produces sporozoites in the salivary glands of Ornithomyia avicularia L. and has been transmitted by the bite of this insect. The parasite has also been isolated from naturallyinfected O. avicularia. Observations on experimentally-infected birds have shown that the macrogametocytes reach their full size in six days, and the microgametocytes in five. The taxonomy of the genus is briefly discussed.

Notes: SYNOPSIS. Euglena gracilis (strain Z) was grown auto-trophically at different light intensities, saturating or limiting for cell division. Adaptation to culture at each light intensity was gauged from division rate, mass, protein, photosynthetic pigments, nucleic acids, volume, paramylum, lipids, respiration, and photosynthesis. Illumination above 1200 foot-, candles was saturating for all aspects of cell growth; the highest intensity examined (3,000 ft-c) slightly inhibited cell division. Intensities between 400 and 1200 ft-c were saturating for all except photosynthesis and paramylum accumulation. Intensities less than about 200 ft-c became limiting for all fractions except protein, which remained constant over the range 120–3000 ft-c, dropping, however, at 65 ft-c. Concentration of photosynthetic pigments increased as light intensity decreased.Absolute synthetic rates were estimated for the individual Euglena cell for the measured cell constituents. While most followed a predictable pattern, increasing with light intensity to saturating levels, the synthetic rates for the pigments went through maxima at 190 ft-c. Since fixed carbon in limiting light is so apportioned that protein is synthesized to the exclusion of paramylum, one concludes that the energy requirements for cell growth (measured as protein synthesis), and to a lesser extent cell division, have a higher priority than do those activities concerned more directly with maintenance.

Notes: SYNOPSIS. Nucleocytoplasmic relationships were explored by producing the extreme alterations in proportion of macronucleus to cytoplasm for which the ciliate Stentor coeruleus is uniquely suitable. Cytoplasmic volumes were varied from about 40 to 6000 times the nuclear volume, as compared with a normal range of approximately 126 to 387. 1. Neither gross reduction nor great excess of the nuclear complement stimulate or inhibit cell division; for division never promptly ensued nor were giant cells or dwarf lines produced. Previous studies(5) have shown that lesser variations in nucleocytoplasmic proportions also have none of these consequences. 2. Hypernucleation produces no noticeable accelerating effect on cell re-differentiation (oral regeneration), ciliary activity (swimming and feeding), or growth and multiplication. 3. Overnucleation is adjusted by extensive fusion of macronuclear nodes (reducing nuclear surface area) and by gradual resorption of some of the nucleus. 4. Nucleus maximally reduced to one node in normal and greater amounts of cytoplasm almost always results in delays of 2 to 15 times the usual preparatory period for regeneration as well as diminished feeding and impaired digestion, and acts as a stimulus to reorganization—confirming Schwartz(27). In hyponucleates there is a compensatory increase in nodal number following regeneration, reorganization (or division), but only after oral primordium formation—again confirming Schwartz. At least two such formations (regeneration followed by reorganization or division) are required for recovery of a nuclear complement of normal proportions, and this very probably represents a true increase in macronuclear substance as well as in number of nodes.6. In division the number of macronuclear nodes is approximately doubled, such that each fission product begins with about the same number as the parent cell, but the new nodes are generally smaller. Whether, during interfission, a regular increase in size of nodes and the addition, at most, of 3 new nodes represents a real increase in nuclear substance is questionable in view of the fact that isolated single nodes remain as such for days without increase until oral primordium development. Cytosomal events may be said to give the stimulus to renodulation and possibly also to macronuclear growth as they do for micronuclear growth in mitosis.7. When the nucleus is maximally reduced, the single node may be resorbed and no oral regeneration occurs. Alternatively, the macronuclear bead supports delayed regeneration but fails, temporarily or permanently, to increase itself. Less commonly, neither oral nor nuclear regeneration occurs though the single node persists. All indicate a statistical probability of some injury to a reduced nucleus when in an excess of cytoplasm. 8. Early oral primordia are resorbed in regenerators (and dividers and reorganizers) when the macronucleus is reduced to one node, but the single node which could not support continued regeneration is nevertheless sufficient for subsequent re-regeneration. 9. At most the oral primordium can develop 3 steps further (more often 2, sometimes none) after complete enucleation. Hence there is little storage of nuclear support. Stage-5 anlagen, still without visible trace of mouth-parts, can develop fully, suggesting there is little synthesis of materials in later development but largely morphogenetic movements of invagination and translocation in completion of the feeding organelles.10. Enucleated stentors can feed quite well at first but not at all later. All indications are that they are incapable of digesting food organisms. Mononodal stentors fare somewhat better and recover normal function as they regenerate the nuclear chain. Enucleates die on the average sooner than starved nucleate controls, but there is considerable overlap in survival times.Some inferences from these findings are discussed. In experiments with other concerns, a sufficient amount of macronucleus should be used or retained, else the disproportion becomes a factor in itself.

Notes: SYNOPSIS. The motility of Tetrahymena pyriformis is inhibited by quaternary ammonium compounds of the type that has neuromuscular blocking activity (such as decamethonium salts). The effect on the cell is reversible by dilution and appears to be non-lethal for prolonged periods. Curare has no effect at concentrations tested. Paramecium caudatum appears to react similarly to T. pyriformis. The results are discussed in view of acetylcholine mediated ciliary beat.

Notes: SYNOPSIS. A leptomonad zooflagellate infecting the macronucleus of Paramecium trichium is described. The cell body of Leptomonas karyophilus n. sp. is 5μ long and the flagellum is 12μ long. There is a central ovoid nucleus, a bar-shaped kinetoplast and a contractile vacuole. The flagellate undergoes division in the macronucleus, proliferating there until it has killed its host. Mildly infected paramecia are able to divide and if fed regularly can be maintained carrying the parasite. Cross infections with P. caudatum, P. bursaria and P. aurelia were successful to varying degrees.

Notes: SYNOPSIS. The carbonic anhydrase inhibitor 2-acetylamino-1,3,4-thiadiazole-5-sulfonamide-sodium prevents mineralization in the coccolithophorid Hymenomonas sp. in concentrations which still permit the growth of organisms.

Notes: SYNOPSIS. A study of regeneration of trichocysts in Paramecium caudatum was made in the electron microscope. Organisms, from which trichocysts were removed en masse with electric current, were allowed opportunity to regenerate their lost organelles before they were prepared for microscopical examination of developing stages.Thin sections of organisms from various regeneration periods demonstrate clearly the endoplasmic origin and development of trichocysts. The first stage seen is a membrane-limited, endoplasmic vesicle enclosing an homogeneous mass, the primordium, within which appears a minute, point condensation of greater electron density. This is subsequently elaborated as a closely packed system of linearly oriented fibrous elements (30–50 Å)—the first definitive sign of the presumptive trichocyst. By progressive utilization of the intra-vesicular primordial matter in association with apparently continuous provision of the building material by extra-vesicular biosynthetic activity, the form and structure of the juvenile trichocysts recognizable as a system of closely packed, multi-layered, fibrous sheets become increasingly evident. The basic structural patterns extend also into the now developing tip. Further growth and differentiation involving the transition of its gross shape from oval to oblong effect a second notable morphological transformation: the formation of a dense U-shaped cortex enclosing a lightly stained center. Full maturation of the trichocyst includes the formation of the cap, disappearance of the limiting membrane, reduction and ultimate loss of the dense cortex with simultaneous assumption of light electron stain homogeneity of the body, and elaboration of the characteristic periodic striation of the tip. These neo-formative events, which also occur—although with reduced frequency—in normal vegetative forms, in conjugating pairs, and in dividing organisms, are concluded prior to the final positioning of the organelle in the bipolar ciliary meridian.The implications of these findings are discussed in light of current hypotheses concerning the role of the nucleus and ciliary basal bodies in the genesis of cortical organelles.

Notes: SYNOPSIS. Genus Haplosporidium Lühe, 1900 (=Aplosporidium Caullery & Mesnil, 1899) now contains an incoherent group of about 25 species with spores of very diverse morphological types or with spores unknown. Therefore, such limited revision of the genus as present knowledge permits is proposed. H. scolopli (C. & M., 1899) Lühe, 1900, is selected from the two genosyntypes as type species. An essential generic character is that the anterior end of the spore opens like a lid to provide an orifice for emergence of the sporoplasm. The following nine species are rejected because their spores seem to lack the lid (operculum, clapet): H. mytilovum Field, 1924; H. gammari Van Ryckeghem, 1930; H. aulodrili Jírovec, 1940; H. ecdyonuris Weiser, 1947; H. bayeri Weiser, 1947; H. aselli Pflugfelder, 1948, H. tapetis Vilela, 1950; H. periplanetae Georgevitch, 1953; H. typographi Weiser, 1954. H. chitonis (Lankester, 1885) Debaisieux, 1919, must, in accordance with the law of priority, be put back into genus Minchinia which was created for it by Labbé in 1896 and erroneously suppressed by Debaisieux in 1919. Therefore, its correct name is M. chitonis (Lankester, 1885) Labbé, 1896, and genus Minchinia is restored. The type species of Haplosporidium and Minchinia, H. scolopli and M. chitonis, are deemed to have distinctive characters of generic rank which justify conserving both genera. Species with the lid lying over the orifice, rather than in it, and extending beyond the perimeter of the orifice are transferred from Haplosporidium to Minchinia. The latter then contains eight species: M. chitonis (Lankester, 1885) Labbé, 1896; M. limnodrili (Granata, 1913); M. nemertis (Debaisieux, 1919); M. cernosvitovi (Jírovec, 1936); M. dentali (Arvy, 1949); M. sp. (Sprague, 1954); M. pickfordae (Barrow, 1961); M. costalis (Wood and Andrews, 1962). Left in Haplosporidium, with reservation in the last two cases, are eight species: H. scolopli (C. & M., 1899) Lühe, 1900; H. heterocirri (C. & M., 1899) Lühe, 1900; H. vejdovskyi C. & M., 1905; H. marchouxi C. & M., 1905; H. potamillae C. & M., 1905; H. caulleryi Mercier & Poisson, 1922; H. ascidiarum Duboscq & Harrant, 1923; H. sp. Dehorne, 1935.

Notes: SYNOPSIS. Free amino acids in extracts of a number of tetrahymenid genera, species and strains of Tetrahymena pyriformis were separated by a combination of paper electrophoresis at pH 1.9 and descending paper chromatography with lutidine as solvent. Ethanol extracts of ciliates cultured at temperatures of either 15°, 25° or 35°C were used. Relative evaluation of ninhydrin spot intensity was made for T. pyriformis strains WH52, UM226, hybrids No. 25, No. 76, PR, HS and N. Extracts from 15° and 25°C cultures of T. limacis, T. setifera HZ1, T. vorax V2, Glaucoma chattoni A and Colpidium campylum C were analyzed in the same way.Seventeen spots were usually found on all chromatograms indicating the presence of the substances alanine, arginine, aspartic acid/asparagine, cysteine/cystine, glutamic acid/glutamine, glycine, histidine, leucine, lysine, methionine, phenylalanine, proline, serine, taurine, threonine, tyrosine and valine. No cysteic acid was demonstrable. Cysteine/cystine, histidine, phenylalanine and taurine generally occur in relatively low concentrations or appear to be absent. Those ranked as generally abundant include aspartic acid/asparagine, arginine, serine and threonine. Spot intensities for the remainder of those listed above indicate they were very abundant in most samples.FAA analyses have now been made by us, including those in a previous report, on tetrahymenid ciliates belonging to 3 genera (Colpidium, Glaucoma and Tetrahymena), on 4 species of Tetrahymena (limacis, setifera, vorax and pyriformis) and on 11 strains of T. pyriformis. Although extracts have been compared from ciliates grown at temperatures of 10°, 15°, 25° and 35°C, no striking differences in the qualitative or quantitative composition of the known amino acids in these patterns were observed. It was not possible to establish correlations with serotypes, and no features that might serve as useful taxonomic criteria were observed.

Notes: SYNOPSIS. In axenic culture, the polymorphic ciliate, Tetrahymena patula, consists of two cell types, a small mouthed form (microstome) and a larger carnivorous macrostome both of which possess the tetrahymenal-type buccal apparatus. With the exception of over-all size, only minor differences were found in the structure of the oral area of the two cell types.Each of the membranelles, which lie on the left wall of the buccal cavity, consists of three long rows of kinetosomes with attached cilia. A series of parallel fibers originating at the base of the inner row of kinetosomes in each membranelle runs toward the adjacent, lower membranelle or in the case of the third membranelle toward the junction of the left and right walls of the buccal cavity. After a short distance, a portion of each fiber rises and subdivides to form a periodic array of fine fibrils which lie immediately under the pellicle and run parallel with the long axes of the membranelles. The remaining portion of these kinetosomal fibers continues through the cytoplasm to connect with the kinetosomes of the next membranelle.The undulating membrane, which borders the right wall of the buccal overture, consists of a single row of cilia. Examinations of thin sections show, however, that there are actually two rows of kinetosomes in the membrane base. The outer row is ciliated while the inner row of kinetosomes, which are alternately spaced relative to those in the outer row, lies deeper in the cytoplasm and has no cilia. Fibers project straight down from the base of kinetosomes in both rows and join to form a tangled network which underlies the entire length of the membrane.The oral ribs begin near the base of the undulating membrane and descend in decreasing number to the cytopharynx. There is a connection between the fiber system of the undulating membrane and the tips of the oral ribs. The ribs appear in cross section as raised, thickened ridges of the inner pellicular layer with the outer layer adhering only at the top of the ridges. Immediately underlying the oral rib area is a relatively thick differentiated layer composed of fine fibers within a ground substance.

Notes: SYNOPSIS. Cell volume and nuclear volume measurements were made on Tetrahymena pyriformis strain E cells that had been either (a) suspended in a medium deficient in some nutrient or (b) suspended in a medium containing a metabolic inhibitor. Media deficient in a nucleotide or containing nucleotide analogs did not significantly inhibit growth. However, cell volume changes were observed for cells grown on nucleotidedeficient medium. Amino acid deficient medium inhibited growth completely and both cell and nuclear volume decreased significantly. The minimal volumes attained were 2/3 of the control volume. Media containing amino acid analogs did not completely inhibit growth nor did appreciable volume changes occur. Both cell and nuclear volumes were closely intercorrelated throughout the results.

Notes: SYNOPSIS. Cell volume and nuclear volume of Tetrahymena pyriformis strains HS and E, grown on a defined medium, were measured as a function of age of culture, age of cell and generation time. The volume of an “average” single cell between divisions was calculated for logarithmic phase cultures by using volume distributions and difference equations. Cell volume measurements were made by compressing the cells to known thickness and measuring the area from photomicrographs. The nuclear volume was determined from diameter measurements of the nucleus by assuming the shape of a sphere.The cell volume decreased from the lag phase to the logarithmic phase and reached a minimum at the end of the logarithmic phase. It increased again during the stationary phase. The nuclear volume also decreased from the lag to logarithmic phase, but continued to decrease in the stationary phase until it reached the nuclear volume of the daughter cell. The average single cell volume increased at a constant rate for 85% of the generation time, at which point the rate diminished to zero. The nuclear volume showed no increase until 35% of the generation time had passed. It then increased at an accelerated rate which diminished just before division. Both the average cell and nuclear volumes decreased with increase in temperature until the optimum temperature was reached, at which point they increased again. There were no appreciable differences in volume changes for cells grown on different media.

Notes: SYNOPSIS. Axenic and monobacterial cultures were utilized to study the ultrastructure of the amoeboid and flagellate stages in the life-cycle of Naegleria gruberi. The cytoplasm of the amoeboid stage is poor in electron-dense components; a loosely organized endoplasmic reticulum is present. The absence of cytoplasmic inclusions in the ectoplasm is the only detectable difference between it and the endoplasm. The nucleus of Naegleria is typically vesicular. The mitochondria are of the type commonly found in protozoa. Food and contractile vacuoles are described. No Golgi apparatus has been found.The general ultrastructure of the flagellate resembles that of the amoeba. The kinetic apparatus consists of flagella and their associated kinetosomes, a “spur” made up of isodiametric fibrils (14 mμ in diameter) attaching to the base of the kinetosome, a cross-striated rhizoplast, and thin-walled fibrils (22 mμ in diameter) with a center of attachment in the kinetosomal complex.Neither centrioles nor kinetosomes have been found in the amoeba. Complex arrangements of endoplasmic reticulum have been seen in the cytoplasm of transforming individuals which may be points of origin of the kinetosomes and/or flagella. The nuclei in metamorphosing individuals frequently show unusual plasticity.Some speculations on possible orgins and affinities of Naegleria are included.

Notes: SYNOPSIS. The subcortical network identified as a leucoplast in Polytoma by some light microscopists actually consists of a system of branching mitochondria. A starch-bearing plastid which may also contain stigma granules occurs beneath the mitochondrial layer. Tubular profiles in the plastid similar to those seen in a Chlamydomonas mutant may be significant to the hypothesis of the origin of Polytoma from a Chlamydomonas-like organism by step-wise loss of chlorophyll-synthesizing ability. The basal bodies of the two typical flagella are connected by an additional broad fibril which arches across the anterior papilla.

Notes: SYNOPSIS. Breeding anomalies in an inbred strain (B1) of syngen 1, Tetrahymena pyriformis, are traced to aberrant chromosomal constitutions of the micronuclei. The origins of the micronuclear defects have not been established, but they probably arise in much the same manner as those observed earlier in “semi-amicronucleate” clones, except that they occur later and in lower frequencies. The abnormal nuclei are impaired in their ability to carry out the maneuvers required for normal conjugation; some are blocked in MI, most after MII; the occasional cells in which nuclear reorganization is completed have visibly defective macronuclear anlagen and are inviable. When crossed to normal strains, nuclear misbehavior is induced in them and again very few if any viable exconjugants are produced. The details of the aberrations are discussed with reference to the patterns of nucleocytoplasmic interaction in conjugation.

Notes: SYNOPSIS. Mechanically released sporocyts of Eimeria bovis, E. ellipsoidalis and E. auburnensis readily excysted when incubated in a mixture of trypsin, steapsin, and bovine bile. Excystation of intact E. bovis, E. ellipsoidalis and E. auburnensis oocysts occurred after pretreatment at 37°C in aqueous 0.02 M cysteine hydrochloride under an atmosphere of CO2-air or CO2-N2, followed by incubation in an enzyme-bile mixture. Nine % of E. bovis oocysts were activated after 6 hr of incubation at 37 C in a mixture of 0.5% (w/v) trypsin, 0.5% (w/v) steapsin, and 5.0% (v/v) bile at pH 7.5 with 10 hr pretreatment under air and 20% CO2; with 30% CO2, 80% activation occurred; with 50% CO2, 91% of the oocysts were activated. At CO2 levels from 10 to 40%, pretreatment with CO2 and N2 yielded less activation than CO2 and air. Pretreatment with CO2-N2 (50–50) for 2 hr resulted in 37% activation; for 6 hr, 60%; for 10 hr, 94%; and for 14 hr, 99%. After pretreatment under 50% CO2 for 10 hr, 95% excystation was obtained by incubation for 6 hr in 0.5% trypsin and 5.0% bile. Only 76 or 69% excystation occurred when 0.25% trypsin or 1.0% bile, respectively, was substituted. Addition of steapsin to this mixture caused little change in the results. In oocysts pretreated 14 to 21 hr with steapsin, 2% or less excystation occurred after 6 hr in a trysinbile or bile mixture. E. ellipsoidalis oocysts, pretreated for 10 hr under CO2-N2 (50–50), underwent 61 and 80% excystation when incubated for 2 and 6 hr, respectively, in trypsin, steapsin, and bile. E. bovis oocysts enclosed in a dialysis bag inside an intestinal fistula became thinned or flattened at the micropyle after 24 hr, and excystation occurred when these oocysts were mixed with trypsin, steapsin, and bile and returned to the fistula for 4 hr. No excystation occurred when oocysts without added enzymes were left 48 hr in the fistula. Sporozoites escaped first from sporocysts and then from oocysts.

Notes: SYNOPSIS. A study, based on tissue and blood smears, has been made of the incidence and intensity of Leucocytozoon in 193 yellow-billed magpies. Tissue smears had a significantly higher gametocyte frequency, as well as a higher density level than was found in the blood films. Three hundred and seven adult magpies were examined for relationship of season to blood-parasite incidence. Both incidence and intensity, as indicated by blood smears increased during the spring months; the peak occurred in March; the lowest findings were in August and September. Data from tissue smears indicate a high incidence throughout the year.

Notes: SYNOPSIS. An occurrence of the allogromid genus Shepheardella is here reported for the first time from the western hemisphere. The foraminifer is briefly redescribed and illustrated.

Notes: SYNOPSIS. A comparison of the effects upon trypsin-dispersed chick liver cell cultures of a virulent (Jones' Barn) and a non-pathogenic (Lahore) strain of Trichomonas gallinae revealed significant differences in behavior of the parasites in cell cultures and in the response of such cultures. The virulent strain multiplies faster in nutrient medium in the presence of cell cultures; stimulates great activity of the macrophages; is not handled effectively by these phagocytes in which it can multiply causing their ultimate destruction; is found significantly more often within the cytoplasm of the liver epithelial and fibroblast-like cells; causes very much more profound degenerative changes in all the cells, both invaded and non-invaded; and suppresses effectively the division rate of the fibroblast-like cells. On the other hand, the nonpathogenic strain multiplies at a lower rate in the presence of cell cultures; stimulates less activity of the macrophages; is handled readily by these phagocytes in which it multiplies only very rarely, if ever; is found seldom within the liver epithelial and fibroblast-like cells; causes far less degeneration of all the cell culture elements; and suppresses significantly less the dlvision rate of the fibroblast-like cells.At the end of a 20–24 hour period typically only a few living cells are left in cultures exposed even to attenuated isolates of the virulent strain, whereas those inoculated with the mild one do not show much degeneration even after 28 hours. The effects upon the cell cultures of cell-free filtrates of actively growing trichomonad cultures are relatively minor, but the changes caused by the filtrates of cultures of Jones' Barn strain appear to be more extensive than those caused by similar filtrates of Lahore strain.

Notes: SYNOPSIS. An iron deficiency was noted for Tetrahymena grown in a proteose-peptone-yeast extract medium. Thus, the addition of an iron chelate and glucose was found to give consistent and luxuriant growth, whereas a number of other additives, including sodium acetate, an inorganic salt mixture lacking iron, and vitamins were found to be without influence on growth rate or cellular yield.Iron-deficient cells showed a marked reduction of oxidative capacity when suspended in a non-nutrient medium as well as when supplied with oxidizable substrates. A 1 hour incubation of iron-deficient Tetrahymena with iron chelate restored oxidative capacity only when the cells were suspended in a nutrient (peptone) medium. Growth of Tetrahymena in media autoclaved with salts resulted in cells with a larger volume but with no increase in oxidative capacity.The addition of 2,4-dinitrophenol elevated respiration of cells suspended in a non-nutrient medium, and of iron deficient cells suspended in the growth medium, suggesting that this compound increases the availability of iron or iron containing compounds, or by-passes the limiting steps.Respiratory quotients were lowered by an iron deficiency and elevated when the cells were grown in the presence of iron and glucose. This suggests more complete utilization of the carbohydrate, possibly due to the activity of a number of enzymes known to be iron-containing metalloproteins that are required for oxidative glucose dissimilation.

Notes: SYNOPSIS. Small amebas are difficult to describe because of the lack of permanent morphological criteria. Investigations from the nuclear division and physiological points of view may be useful, but the study of motion and behaviour under natural conditions gives better results in order to show the natural relationship. Descriptions of four new forms of small marine amebas are given. These species belong to the genera Rugipes, Acanthamoeba, Flabellula and Vahlkampfia.

Notes: SYNOPSIS. The environmental factors causing encystation in Hartmannella rhysodes, a small soil amoeba, appear to be an elevated osmotic pressure, Ca2+ and Mg2+, aeration and a decrease in carbon sources. After 36 hr under these conditions, amoebae harvested during active growth encyst. Nutrients essential for growth, other than carbon sources, have no effect on encystation. The factors which bring about encystation are components of the defined medium, in which the minimum essential organic requirements for growth are known.

Notes: SYNOPSIS. Methods have been developed for the isolation of deoxyribonucleic acids (DNA) from Tetrahymena pyriformis, Polytomella papillata, and Aspergillus tamarii. The DNA from these organisms contained adenine (A), thymine (T), guanine (G) and cytosine (C), and the usual base-pairing relationship, i.e., A = T; G = C was found. The ratio A + T/ G + C was 2.42, 1.42, and 1.08 for the DNA of the three organisms respectively. 5-Methylcytosine was absent in all cases.

Notes: SYNOPSIS. Seven monoxenous Trypanosomatidae, Crithidia fasciculata (Anopheles strain), C. fasciculata (Culex pipiens, Wallace), C. fasciculata (Culex pipiens, Nöller), C. luciliae, C. sp. from Euryophthalmus, “Strigomonas” oncopelti and Blastocrithidia culicis all are catalase-positive. S. oncopelti is only catalase-positive when grown in hemin-media. When grown at elevated temperature, C. fasciculata (Anopheles), C. luciliae and S. oncopelti have greater and C. fasciculata (Culex pipiens, Wallace) reduced catalase activity. C. fasciculata (Culex pipiens, Nöller) and C. sp. from Euryophthalmus show reduced catalase activity at elevated temperature that is of borderline significance.Catalase as a phylogenetic marker is discussed.

Notes: SYNOPSIS. An electron microscope study has been made of the spores of a microsporidian, Thelohania californica, parasitic in Culex tarsalis. Fresh spores measure 7–9 × 5–6 μ and contain a polar filament which when extruded may reach a length of 150 μ or more. Thus, this is a typical microsporidian spore. The spore is enveloped in a resistant outer membrane. The polar filament is attached to this membrane at the narrow anterior end, runs inward for a distance and is coiled spirally close to the inner surface of the outer membrane. There are 12–14 spiral turns in the majority of the spores. In the anterior five turns the filament is distinctly larger in diameter than in the seven or more posterior coils. The polar filament appears to be tubular, but the lumen is filled partially or completely with material of high electron density. A laminated polaroplast surrounds the basal portion of the filament and extends into the middle and posterior regions of the intrasporal cavity. The sporoplasm is uninucleate and lies in close contact with the polar filament and the polaroplast. There is no polar capsule.

Notes: SYNOPSIS. The effect of H. gallinacea infection on the phagocytic activity of the reticulo-endothelial system in chicks has been investigated. Changes occurring in the pattern of R.E. activity show that there is initial stimulation of phagocytosis within 24 hr and that this increases up to the 4th and 5th days after which time parasites appear in the blood. Thereafter there is a rapid drop in R.E. activity with a proportional increase in parasitaemia following which death ensues. The importance of the protective value of the reticulo-endothelial system is indicated and it is suggested that a toxin produced by the parasites or by their break-down products is the likely cause of phagocytic depression.