ALBERT

Notes: SYNOPSIS. A chemically defined culture medium has been developed for the soil amoeba Hartmannella rhysodes Singh which contains the minimum essential organic requirements for growth. The medium consists of 7 amino acids, 3 vitamins, a carbon source (e.g. glucose) and inorganic salts.

Notes: SYNOPSIS. A mutant strain of Astasia longa utilized glucose for growth whereas the parent (J) strain did not. The optimal pH for growth of the mutant with glucose (sole carbon source) was near neutrality; the optimal glucose concentration 0.02 M. Cell-free extracts or cell homogenates produced C14O2 when incubated in the presence of C14-labeled glucose. On the other hand, after incubation with C14-labeled glucose, intact parent cells and their respiratory CO2 showed no radioactivity while the mutant-strain cells and CO2 produced were active. Dissimilation of glucose-1-C14 and glucose-6-C14 yielded the same amount of radioactivity in metabolic CO2 in cell-free extracts of both strains. Of five enzymes assayed, hexokinase, phosphoglucomutase, and lactic dehydrogenase were present whereas glucose-6-PO4 dehydrogenase and glucose dehydrogenase were absent in cell homogenates of both strains. Presumably these two strains of A. longa differ in permeability of the plasma membrane. Further tracer and enzyme studies indicated that the Embden-Meyerhof scheme is the principal pathway of glucose catabolism; the hexose mono-phosphate shunt and the direct oxidative pathway were either not operating or quantitatively insignificant.

Notes: SYNOPSIS. By means of electron microscopy, a study has been made of the fine structure of the macrogametocytes, microgametocytes and oocysts of Eimeria perforans from the intestine of the wild rabbit (Oryctolagus cuniculus). The parasites lie in a vacuole within the host cell. The surface of the gametocytes is not plain, but displays irregular protrusions. A large intranuclear body can be detected within the macrogametocytes. Similar structures are also found within the cytoplasm. Within the latter there exists a large spread out reticulum, the channels and vesicles of which concentrate especially close to the nuclear membrane. Tubuli are seen in the numerous mitochondria, which often have a dumb-bell shape.In most of the gametocytes irregular, strongly osmiophilic lipid inclusions are observed, which always are surrounded by the endoplasmic reticulum. Strange folded ovoid bodies are found within the cytoplasm of the oocysts. Nothing can be told with certainty of their nature and function. Probably they represent specific storage bodies.

Notes: SYNOPSIS. Tritrichomonas foetus survived much better on extended storage at -95 than at -28d̀C following slow freezing in the presence of 1.0 M glycerol. There was no significant difference between these temperatures in survival up to 8 days, but thereafter the protozoa continued to die off slowly at -28d̀, whereas their numbers remained essentially constant at -95d̀ for 128 to 256 days. The trichomonads' motility was much better after storage at -95d̀ than after storage at -28d̀, and fresh cultures could be initiated from the former much more readily.Other constituents of the suspending medium besides glycerol affect the survival of the protozoa upon freezing. Survival was much better when the protozoa were frozen in the original Diamond's trypticase-yeast extract-maltose-cysteine-ascorbic acid-serum medium in which they had been grown than when they were frozen in physiological salt solution or in fresh Diamond's medium. There was no significant difference between survival in the latter two suspending media. The speed and time of centrifugation needed to remove the trichomonads from the medium in which they had been grown had no effect on their survival upon subsequent freezing. Presumably some product or products of the trichomonads' metabolism have an additional protective action which supplements that of glycerol.When frozen in the original Diamond's medium in which they had been grown plus 1.0 M glycerol, an average of 15% of the trichomonads were alive after 128 days' storage at -28d̀ and an average of 38% were alive at -95d̀C. When frozen in physiological salt solution plus 1.0 M glycerol, these percentages were 8% and 12% respectively.

Notes: SYNOPSIS. When Spathidium spathula was exposed to X-ray doses ranging from 1–25 kr this animal was found to be more radiosensitive than any ciliate previously reported. A dose of 1 kr is sufficient to increase the time of the first generation from 5 to about 5 1/2 hours. A dose of 4 kr is enough to approximately double the generation time. Bacteria in the medium during irradiation do not protect the ciliate against injury. Animals irradiated as dry cysts are only slightly more resistant than vegetative forms, requiring 10 kr to double the generation time. One day after exposure, irradiated lines are uniformly poor in growth rate (0–2 daily divisions), but later a bimodal response is noticed, some lines remaining poor and others recovering. Within 24 hours after treatment, a number of irradiated animals show structural abnormalities and are greatly increased in size. The experiments have not determined the reason for the high sensitivity of Spathidium but have made certain alternatives unlikely.

Notes: SYNOPSIS. When Tetrahymena suspended in water were given increasing doses of radiation, oxygen consumption decreased with increasing dose, reaching 60–90% at 600,000 r. Cells irradiated in 0.07 M phosphate buffer, pH 7.4, showed no significant decrease in oxygen consumption even at 600,000 r. The decrease in respiration observed on irradiation of Tetrahymena pyriformis W in water with 300,000 r of X-radiation was prevented by addition of pyruvate or acetate during or immediately after irradiation. Pyruvate stimulated the respiration of the X-irradiated cells, particularly at 10 and 60 min post-irradiation.Lactate markedly stimulated the respiration of control suspensions of Tetrahymena cells and oxidation of lactate by cells irradiated with 300,000 r was increased by 20 to 100%, depending on the concentration of lactate and the time after irradiation. Pyruvate was considerably more effective than lactate in increasing O2 uptake of X-irradiated cells, particularly at 10 min post-irradiation. Thioctic acid affected neither the respiration of control or X-irradiated Tetrahymena nor the oxidation of pyruvate.The growth lag of Tetrahymena increased proportionately with increasing radiation dose; no cells survived 600,000 r. The presence of metabolites during irradiation did not affect the lag period or subsequent growth rates. The effects observed were discussed in terms of an alteration of the permeability of Tetrahymena after irradiation.

Notes: SYNOPSIS. A full account of the nuclear changes during binary fission and conjugation in a local race of Blepharisma is presented in this paper. The macronucleus consists of 2 nodes connected by a strand. Number of micronuclei varies from 6 to 18. During binary fission, condensation of macronucleus is followed by elongation and thinning of the middle region which finally breaks. Daughter nuclei later attain the typical vegetative form. Notably, during binary fission some micronuclei appear to complete their mitoses by the time the macronucleus attains the condensed form, while others lag behind and exhibit practically every stage of mitosis.During conjugation, from 6 to 10 micronuclei undergo the first pregamic division, the same number through the second division, and two products of the second division take part in the third division. The rest degenerate. Division products of the nuclei in the paraoral region take part in synkaryon formation. The synkaryon undergoes either 2 or 3 divisions. In the former case, of the 4 products, 2 become the macronuclear anlagen, one the micronucleus and the fourth degenerates. In the latter case, of the 8 products, 3 to 4 become the macronuclear anlagen and the rest become micronuclei. Chromatin elimination has been observed during the division of the macronuclear anlage, followed by an extra metagamic fission of the cell.Comparison with two other races from India and an American race indicates considerable diversity in the structure and behaviour of the nuclear apparatus in different races of Blepharisma undulans.

Notes: SYNOPSIS. Females of Heterakis gallinae were separated on the basis of their capacity to transmit the protozoan parasite Histomonas meleagridis. Sections of worms, capable of transmitting the protozoon, revealed the organism in both males and females as well as in the eggs. Infected male worms contained histomonads in the gut wall and the wall and lumen of the reproductive system. Female worms infected with H. meleagridis showed the organisms throughout the reproductive system. Histomonads, found in uterine eggs possessing shells, had a larger nucleus and reduced cytoplasm.Because of the presence of the protozoon among the sperm in the male reproductive system, it is believed the organism can be transmitted to female worms through copulation. The cycle in the worms also supports the assumption that H. meleagridis was originally a parasite of the worm.

Notes: SYNOPSIS. Speculations regarding the mode of transmission of monocystid parasites of earthworms over a period of more than 100 years have never been tested experimentally under controlled conditions. In order to do so a stock of infectionfree Eisenia foetida (Sav.) was raised from cocoons and experimental infections were induced in this host using sporocysts of the gregarine parasites Apolocystis elongata Phillips & Mackinnon 1946, and Nematocystis elmassiani (Hesse, 1909). Experimental infections were obtained by feeding to uninfected worms sporocysts obtained directly from infected host worms. This proved that the intervention of a vector is not a necessary condition of infection. Infections could not be induced by injecting sporocysts through the body wall into the body cavity. Infections are thus probably acquired in nature by the ingestion of sporocysts. Sporocysts do not leave the body of the host by being passed from coelom to lumen of the gut, nor do they pass directly to the exterior through apertures of the body wall. There was no evidence of parasitic autotomy. It is therefore concluded that death and decay of the host is the normal method of dissemination of sporocysts. Sporocysts were not infective after drying in air for three weeks. Other sporocysts lost potency after storage in moist conditions for several months. Infections involving the organisms specified were sporadic and unpredictable; modifying factors, such as variations in host susceptibility and latency in infection, appeared to be operating.

Notes: SYNOPSIS. By an automatic electronic technique—the Flying Spot Particle Resolver—the effect of a wide range of concentrations of vitamin B12 on the size and growth of the B12-dependent Euglena gracilis was studied. Rate of cell growth was directly proportional, and cell size inversely proportional, to B12 concentration. Gross B12 depletion resulted in gigantism and prolongation of generation times.

Notes: SYNOPSIS. Previously, the reproduction-inhibiting effects of ablastin could only be shown in vivo. The present report describes techniques for the in vitro demonstration and titration of this antibody. With a medium composed of Hanks' balanced salt solution, rat serum, lactalbumin hydrolysate, yeast extract and rat blood lysate, blood stream forms of Trypanosoma lewisi can be grown for approximately 24 hours at 37d̀C. Starting with the medium containing normal rat serum and inoculated with adult (inhibited) trypanosomes from infected rat blood, 50% or more of the parasites are in various stages of division after incubation overnight. Under similar conditions with ablastic rat serum, the parasites do not reproduce but remain as adults. If the medium is inoculated with reproducing trypanosomes from the blood, parasites in the presence of normal serum continue to reproduce, whereas those exposed to ablastin are almost completely converted to adult, non-reproducing forms. Similar results are obtained when the immune sera used are first adsorbed with living parasites to remove all trypanocidal antibodies. Ablastic serum inactivated at 56d̀C for 20 minutes does not lose its inhibitory activity indicating that ablastin is not complement dependent, and parasites grown on media at room temperature are not affected by the antibody suggesting that basic antigenic differences exist between blood stream forms at 37d̀C and culture forms at room temperature. Studies of the conversion of blood stream forms to culture forms indicate that the critical temperature range for the conversion lies between 28d̀ and 30d̀C. The significance of these results is discussed, and possible applications of the techniques described to studies of the mechanism of ablastic action are considered.

Notes: SYNOPSIS. Normal swimming behavior of Paramecium multimicronucleatum in an essential mineral element solution with 0.0002 M calcium changed into continuous avoidance reactions upon replacement by equimolar strontium; equimolar barium produced a less pronounced similar effect. In equivalent pure SrCl2 and BaCl2 solutions, avoidance reactions were less frequent than in the balanced solutions. P. multimicronucleatum inoculated into autoclaved calcium- or strontium-containing cultures of the alga Protosiphon botryoides (ultimate food source) multiplied greatly and essentially equally, but died in barium. Accelerated avoidance reaction rates were observed in strontium up to and at 32 days after inoculation.

Notes: SYNOPSIS. A previous study of parasites from relapsed P. berghei infections of mice indicated that the behavior of the relapse parasites differed from that of their parent strain. Experiments have been performed comparing the behavior of relapse and parent parasite infections in mice under two sets of conditions. In one group of experiments the behavior after antimalarial treatments, designed to result in chronic or latent states of infection, was tested. In all, 8 relapse strains were tested against their parent strains in six different experiments which employed 536 mice. It was observed that the mice infected with the relapse strains had a statistically significant greater mortality after the treatments than did mice infected with parent strains. This difference was observed regardless of how the relapse strain had been previously treated, or of what treatment was used in the experiments. In a second group of experiments, the behavior of infections with relapse and parent parasites was compared in normal mice. Five relapse strains were compared to their parent strains in a total of 5 experiments using 356 mice. It was observed that the mean survival time of mice infected with relapse strains was significantly greater than that of mice infected with the parent strains. It is not known whether this apparent difference in the behavior of relapse and parent parasites is related to the mechanism for relapse of P. berghei infections, or is merely a characteristic of parasites that had survived in an immune host.

Notes: SYNOPSIS. Schizonts were found in the middle and lower third of the small intestine of two calves killed 12 and 14 days after they had been inoculated with pure cultures of oocysts of Eimeria auburnensis. The schizonts ranged from 78 to 250 μ long by 78 to 150 μ wide (mean 92 by 139.9 μ). They were usually located deep in the lamina propria near the muscularis mucosae instead of in the villi where most schizonts of Eimeria bovis are found. The schizonts of E. auburnensis resembled the previously described large microgametocytes of this species but were distinguishable morphologically and by histochemical stains. The microgametocytes were much larger than previously reported; one measured 91 by 287.5 μ.

Notes: SYNOPSIS. Three new species of Blepharisma are presented: B. seshachari sp. nov., B. intermedium sp. nov., and B. tropicum sp. nov. Two sub-species of Suzuki are elevated to specific rank, B. undulans americanum to B. americanum and B. undulans japonicum Suzuki to B. japonicum Suzuki. Stein's taxa for the species Blepharisma undulans are considered to be diagnostic for that species.Important features of morphology and life-cycle of the above mentioned species are given. Discussion and position of the species Blepharisma undulans are presented and a proposal for the reorganization of the species is made. The possibility of a new key derived from a hypothesis of the phylogeny on an evolutionary basis of the genus is presented. This hypothesis has been extended to include ciliates like Stentor and Spirostomum and its implications discussed.

Notes: SYNOPSIS. A laboratory colony of Oncopeltus fasciatus was found to be infected with Leptomonas oncopelti. Inasmuch as the parasite is transmitted from parent to offspring an opportunity presented itself to study the biology and transmission of this parasite under controlled laboratory conditions. An apparatus for observing individual bugs was designed and the presence or absence of flagellates in the feces determined. Flagellates were not shed until the bugs became adults after which they appeared in every defecation. Dissection of infected bugs revealed that flagellates were not present in the rectum until adulthood. Further studies indicated that in the midgut of the insect there is a departure from binary fission to budding. The nucleus divides and one of the newly formed nuclei migrates toward a newly formed kinetoplast. Rarely there is still another kinetoplast/nucleus division. In the event the new axoneme grows within the cytoplasmic sheath of the parent flagellum, smaller organisms produced by unequal cytokinesis remain attached. If the axoneme grows free, the smaller daughter organisms become free-swimming. Passage into the rectum of the adult bugs causes a rounding up of all parasites although the leishmaniform organisms continue to divide. It is presumed that infection of clean bugs is accomplished by the ingestion of leishmaniform organisms through a common water source. The reason for the presence of flagellates in the rectum of the adult but not in the nymphal insect and the mechanism responsible for the change from binary to unequal fission are not known.

Notes: SYNOPSIS. Examination of intestinal contents and feces of Wisconsin red squirrels (Tamiasciurus hudsonicus) revealed two coccidia, Eimeria tamiasciuri and E. toddi n.sp. In the Eastern chipmunk (Tamias striatus), two species, E. vilasi n.sp. and E. wisconsinensis n.sp. occurred. In the northern flying squirrel (Glaucomys sabrinus), a coccidium resembling E. sciurorum was found.

Notes: SYNOPSIS. A large heterotrich ciliate (Family: Bursariidae) found in a papyrus swamp in Uganda was used for oxygen tension experiments by Beadle & Nilsson, 1959, under the name of Bursaria sp. This organism has now been identified as Neobursaridium gigas Balech. The morphology of the organism was studied in living and stained specimens, especially with the silver impregnation technique, and the present findings are compared to those of Balech.

Notes: SYNOPSIS. An electron microscope study of thin sections of Babesia rodhaini parasitizing mouse erythrocytes showed that this intracellular parasite feeds on its host cell in the same way as do malarial parasites. Large portions of erythrocyte cytoplasm are engulfed by invaginations of the plasma membrane leading to the formation of food vacuoles. The digestion of hemoglobin seems to be complete in Babesia since no pigment (hemozoin) could be detected either in the food vacuoles or in the cytoplasm.The fine structure of Babesia rodhaini is very similar to that of Plasmodium berghei. In both, typical mitochondria are lacking. Instead a structure was found composed of concentric membranes which it is assumed might perform mitochondrial functions. As in Plasmodium berghei a double-membraned vacuole with a matrix of low density is present in almost all sections. The endoplasmic reticulum is represented by small vesicles; the ground-substance is filled with Palade's small particles. The nucleus is large and surrounded by two membranes. Babesia reproduces by budding and binary fission. Reproduction is not easy to identify since the parasite forms large pseudopods resembling stages in division.

Notes: SYNOPSIS. The effect of 10 detergents on the inhibitory activity of neomycin was tested against Ochromonas danica. All 4 anionic detergents used were synergistic with neomycin. Evidence is presented that the synergisms were due to the effect of the detergents on the cell membrane. In the presence of Tergitol 7, O. danica is more susceptible to changes in osmotic pressure by increasing concentrations of KCl.

Notes: SYNOPSIS. All zoologists are affected by provisions in the very recently published International Code of Zoological Nomenclature, the first revised edition of these important rules to appear in over 50 years. Common nomenclatural practices, often malpractices, of protozoologists and parasitologists who work primarily in taxonomic fields are revealed and discussed in light of recommendations and mandatory regulations to be found in the new Code. Some errors have been due solely to carelessness; others have involved misinterpretations of various directives; still others have involved cases not adequately covered by the old Règles. Certain mistakes of the past cannot be changed; but others are to be rectified upon discovery, according to mandates in articles of the new Code. Practical applications of the rules of nomenclature are stressed, and examples are taken from actual situations found to exist throughout all major taxa of the phylum Protozoa.Because of the value of such discussion in both new and revisory work in protozoan systematics, the following major topics are given special consideration: matters of orthography, the original spelling of names and their justified or unjustified emendation; authorships and dates of names, who is responsible and when, and how such data are properly cited; mandatory dates in the new Code, and their effect on both already established names and names not yet proposed; the principles of priority and conservation or continuity, and how the rules attempt to satisfy proponents of both of these diametrically opposed “laws”; the concepts of synonymy and homonymy, and proper methods of treating names which have become involved in such situations; family-group names, and the several special nomenclatural problems they present to protozoan taxonomists; the major problem of types, and the peculiar position of protozoologists with regard to the type concept, especially type-specimens for categories in the species-group; miscellaneous considerations, several unrelated but significant topics not appropriate for inclusion in preceding sections of the paper.

Notes: SYNOPSIS. In a chemically-defined medium Tetrahymena setifera HZ-1 required a sterol, an alcohol, eleven amino acids, a purine, a pyrimidine, and six B-complex vitamins. The sterol requirement was met by a variety of 3β-OH, C27-C29 sterols including cholesterol and stigmasterol, but not by precursors of cholesterol which precede desmosterol or Δ7-cholestenol. Some combinations of long-chain fatty acids with a synthetic dipalmitoyl phosphorylethanolamine partly substituted for sterol. Ethyl and methyl alcohols (but not a variety of other alcohols and organic acids) satisfied the alcohol requirement.

Notes: SYNOPSIS. Trichomonas vaginalis grown aerobically slowly metabolizes glucose-U-C14 and succinate-2,3-C14 to CO2 and to amino acids which are then incorporated into protein. Analysis of protein hydrolysates from cells grown on glucose-U-C14 reveals radioactivity in 15 amino acids. Although the data do not permit a direct interpretation and analysis of the sequence of amino acid biosynthesis, it seems likely that a tricarboxylic acid cycle operates. Attempts to prepare cell-free systems carrying out cycle reactions have proved unsuccessful.

Notes: SYNOPSIS. One hundred eighty-eight fresh-water samples from France (30), Italy (42), Austria (12), Germany (1), Switzerland (35), Holland (20), England (26), and Sweden (22) were examined for T. pyriformis. The habitats included rivers, mountain streams, lakes, ponds, irrigation ditches, roadside ditches, running and dead water canals, and fountains. The temperature ranged from 10° to 30°C, locations from 42° to 68° North latitude, with elevations from sea level to approximately 3,000 feet. Of the samples taken 28 contained T. pyriformis from which 411 clones were established in axenic media. Thirty-three additional samples contained ciliates other than T. pyriformis. All clones grew well in 1% proteose peptone; when screened for their nutritional requirements a few failed to grow on the completely defined medium and several others survived eight sub-inoculations without thiamine.The nuclear and sexual activity pattern followed that of previous collections. In distribution, variety 6 was found in Italy, variety 3 in Austria, and variety 4 in England. A new variety (variety 10) with two mating types was isolated from four different habitats in England. Several strains from Italy, France, Holland, and England constitute one group which mated among themselves, but only a few of which reacted with mating type I of variety 6 from America. This demonstrates the close affinities of the European and American strains, yet shows the possible evolution of a new variety (species).

Notes: SYNOPSIS. The steroid requirement of a Trypticase-requiring strain, SLT, of Trichomonas gallinae on the Shorb-Lund synthetic basal medium minus ribonucleic acid was fulfilled by cholesterol, 7-dehydrocholesterol(provitamin D3), cholestanol (dihydrocholesterol), and to a lesser degree, by ergosterol (provitamin D2), β-sitosterol and zymosterol acetate. Cholestanol was inhibitory at certain concentrations. All steroids were subsequently checked by gas chromatography. Only cholesterol and zymosterol acetate showed one peak, the others containing 2 to 4 peaks. Repurified cholestanol was active and showed no inhibition of growth, but repurified β-sitosterol was inactive. The following were also inactive: diethylstilbestrol, estrone, dehydroepiandrosterone, progesterone, testosterone, desoxycorticosterone acetate, cortisone acetate, compound A, 5,6-dihydro-ergosterol, dihydroergosterol acetate, stigmasterol, sodium taurocholate, cholic acid, methyl desoxycholate, desoxycholic acid and methyl cholate. Precursors in cholesterol synthesis, acetate, mevalonic acid, mevalonic acid plus a liver extract and squalene were inactive in replacing cholesterol, although acetate is required for growth in the presence of cholesterol. Crystalline fat soluble vitamins, carotene, calciferol (vitamin D2), activated 7-dehydrocholesterol (vitamin D3), menadione (vitamin K3) and tocopheryl acetate (vitamin E acetate) were inactive in replacing cholesterol. Trichomonas species PN from the pig's nose utilized cholesterol, 7-dehydrocholesterol and the impure β-sitosterol sample in a modified SL medium with acetate omitted. A reinvestigation of steroid requirements seems to be indicated when a completely synthetic medium and pure steroids are available.

Notes: SYNOPSIS. Protoplasm transferred to a multinucleated amoeba is well tolerated if the donor and recipient portions are from the same amoeba, from different amoebae of a single clone, from different amoebae of the same species found in a given location, or from different amoebae of the same species found in widely separated geographic areas. On the other hand, protoplasm is not tolerated and death invariably follows interspecific or intergeneric microtransfers between any two of the three species of amoebae used in this study.Attempts to overcome the tolerance block in heterologous transfers by the use of x-radiation failed although a significant extension of the mean survival time was obtained. The latter can also be interpreted as a limited therapeutic effect of nonirradiated, heterologous donor protoplasm on supralethally irradiated recipients.

Notes: SYNOPSIS. Cultures of Prymnesium parvum subjected to constant illumination failed to produce ichthyotoxin. On the other hand cultures subjected to alternate periods of light and darkness showed a gradually rising ichthyotoxic activity during the dark period reaching a maximum after about 7 hours.

Notes: SYNOPSIS. A new species, Crithidia rileyi (Trypanosomatidae), is described from Tabanus epistates. The most characteristic feature of the flagellate is the frequent occurrence of a broad sucker-like posterior end. In contrast to other species of Crithidia it multiplied very slowly in the first few weeks after isolation. A review of the literature shows that trypanosomatids of two generic types, Crithidia and Blastocrithidia, have been described from flies of the family Tabanidae, although they have nearly always been regarded as stages of the same organism. Some or all of those of the Blastocrithidia type are stages of Trypanosoma theileri. The Crithidia are probably not stages in the development of any trypanosome.

Notes: SYNOPSIS. Gromia oviformis from New Zealand has been examined in thin sections after fixing in osmium tetroxide and embedding in methacrylate. The structure of the protein and acid mucopolysaccharide shell and the canals which pass radially through it are described. Multiple honeycomb membranes located between the shell and the cytoplasm, as well as mitochondria and “Golgi bodies,” none of which has hitherto been seen in light microscope studies, are discussed and illustrated. The previously known stercomata and xanthosomes are considered. Though still regarded as enigmatic cytoplasmic inclusions, observations suggest that they are waste products retained within the animal throughout life.

Notes: SYNOPSIS. An agar overlay technique developed to investigate the effect of various substances on growth of a selected group of protozoa is described. Test systems employing Crithidia fasciculata (culex), Ochromonas malhamensis, Tetrahymena pyriformis W and Trichomonas foetus were devised to evaluate the effect of known compounds and to assay the activity of antibiotic fermentation beers. This disc-plate method can be summarized as follows: preparation of a foundation layer; overlaying of a mixture of agar, nutrients, protective antibiotics, and inoculum; placing of paper discs with the test material on the overlay followed by incubation and subsequent observation of the plates for zones of inhibition of growth. The concentration of agar in the overlay sufficient to restrict movement of the protozoa without inhibiting their growth, nutrients required for adequate growth and continued viability of the inoculum, and the concentration of penicillin and streptomycin which will not inhibit the assay protozoa but beeffective against the microorganisms in the fermentation beers are discussed. This technique offers a method not only for primary screening for cytotoxic substances but also one which may be adaptable to other studies of protozoa.

Notes: SYNOPSIS. Acid phosphatase activity was studied in total mounts and sections of agnotobiotic Paramecium multimicronucleatum by the alpha-naphthyl phosphate-hexazotized rosanilin method. Timing was achieved by India ink marking of food vacuoles. Enzyme activity is present in small endoplasmic granules and in the greatest part of food vacuoles. Following an inactive stage (stage I) of an average length of 5 min the activity appears at the periphery of the vacuole, in most cases in the form of granules (stage II). A high activity level (stage III) is attained within 1 1/2 min and maintained for the most part of the vacuolar cycle. The activity disappears only in the latest vacuoles before egestion (stage IV). The appearance of activity is not concurrent with but succeeding to the maximum of vacuolar acidity as ascertained by feeding Congo red stained killed yeast cells. On the basis of these results the food vacuoles may be looked upon as belonging to the lysosomes sensu lato.

Notes: SYNOPSIS. In Oxytricha fallax, extrusion of all the excretory crystals and some refractile bodies occurs when food is with held. The precystic animals thus resulting become transparent and undergo dedifferentiation of organelles. First the undulating membrane and cytostome are entirely resorbed, producing astomial forms. Then the adoral membranelles vanish gradually, accompanying which the somatic ciliature such as the cirri comes to be resorbed. Occasionally, early precystic animals retaining the intact feeding organelles reorganize spontaneously (physiological regeneration), but they become irreversibly encystable by high-temperature treatment; for hastening resorption of feeding organelles accelerates encystment.When transparent animals at various precystic stages are cut in half the posterior fragment (PF) always encysts faster than the anterior one (AF) from the same parent, except that some of the AFs from early stages reorganize into normal vegetative forms. The time difference for completion of encystment between an AF and PF pair is at early stages larger than at later ones. If the anterior part of AF is further excised, the time difference for encystment between AF and PF from the same source becomes smaller or indistinguishable, with the exception that some AFs from early stages regenerate instead. Further, when the anterior part of whole precystic animals is removed, the time for their encystment is reduced. Also in this case, the fragments from early stages normally regenerate.From these results, it is presumed that the adoral membranelles tend to inhibit the encystment process as they do the initiation of an oral primordium in dividers and regenerants of Stentor and other ciliates. Accordingly, when resorption of membranelles becomes extensive as precystic processes progress, their dominance over and inhibition of cyst formation may be diminishing. From the fact that regeneration of fragments from early stages into normal forms may be due to retention of the undulating membrane, its resorption is considered to be an essential prerequisite for the initiation of irreversible encystment.

Notes: SYNOPSIS. A partially purified hexokinase extracted from Euglena had the following properties: 1) pH optimum 8.0–8.5; 2) an absolute requirement for Mg++ and adenosine triphosphate with Mn++, Co++, Zn++, and Ca++ less active or inactive under the test conditions. Inosine triphosphate could not be substituted for adenosine triphosphate; 3) an apparent Km (glucose) of 5 × 10−4 M; 4) the enzyme was not inhibited by the usual sulfhydryl agents, but was inhibited 24% by adenosine diphosphate. The extract phosphorylated fructose and mannose. It was not clear whether a separate enzyme phosphorylated fructose. Relative rates of phosphorylation, as determined by labile phosphate analyses, were: glucose, 1.00; fructose, 1.19; mannose, 0.56. The partially purified extract also contained phosphohexose isomerase activity; 6-phosphogluconic acid dehydrogenase was absent. Euglena hexokinase is apparently localized in the cytoplasmic or small-particle fraction of the cell. In most respects the enzyme seems to resemble the well-characterized yeast hexokinase rather than the muscle enzyme.

Notes: SYNOPSIS. Lankesterella bufonis sp. nov., from toads, Bufo regularis Reuss, in Egypt, described herein, appears to be the first species of this genus to be found in Bufo. Sporozoites of the parasite in circulating blood are usually intracorpuscular, rarely free. Free forms, abundant in smears of internal organs, particularly from lungs, are small, slender, slightly curved bodies with the anterior end more pointed than the other. The small, oval, delicate nucleus is always situated in the posterior third of the parasite, either terminal or more usually subterminal. A single cytoplasmic vacuole is located just anterior of the nucleus and more-or-less centrally. Few darkly stained granules are sometimes seen around the vacuole. Though intracorpuscular forms retain morphological characteristics of the free forms, they frequently undergo peculiar changes: apparently flattening of host-cells during smearing and fixation results in shorter and wider, and sometimes greater width of the parasite. Multiple infection with two and rarely three Lankesterella sporozoites is not uncommon. In liver and spleen smears, certain large cells, apparently of the macrophage or endothelial types, contain forms similar to those described in the peripheral blood, but mostly shorter and broader. Various developmental stages of schizonts were also seen in the liver and lung. In liver, lung, spleen, and kidney sections, numerous young forms, possibly merozoites, were scattered among tissue cells. The present parasite differs morphologically from Lankesterella minima (Chaussat, 1850), L. monilis Labbé, (1894), and L. canadensis Fantham et al., 1942.

Notes: SYNOPSIS. Ophryoglena mugardi is an Ophryoglena of medium size characterized by its spindle-shaped and bimicronuclear theront, by its rather bulky trophont and by its physiological reproductive cycle. During starvation its physiological evolution causes a secondary and temporary encystment of the theront lasting 6 or 7 days (at 18°C). The ultimate re-encystment leads to cytolysis. Feeding induces the physiological reproductive cycle; if food is given soon after the release of the tomites, it determines a primary cycle, usually allowing eight tomites; if it is dispensed only after the secondary encystment of the hungry theront and after its excystment it causes the appearance of secondary cycles, allowing two or four tomites.When the starved theront, becoming smaller and smaller, is fed it produces trophonts which encyst. These no longer divide; each one delivers one theront only. These theronts, smaller and smaller, are able to produce the original major forms, but only after several successive alimental cycles and without any secondary encystment of the theront.

Notes: SYNOPSIS. The plastid system of “normal”Euglena gracilis strain Z was found to be extremely unstable. Under normal culture conditions in the light about 1 or 2% of the cells were found to have lost spontaneously the capacity to green on further culturing. Cells treated with streptomycin, heat or U.V. all lost the capacity to green on further culturing. Bleached cells whether appearing spontaneously or by induction with streptomycin, heat, or U.V. light, were all found to possess within them organelles which were identified as proplastids.The proplastids of some “bleached” strains were capable of synthesizing porphyrins when grown in a standard culture medium. Others synthesized porphyrins only after the addition of delta-aminolevulinic acid to their medium, while proplastids of still other strains could not synthesize porphyrins from this precursor. Normal cells when grown in total darkness were found to possess proplastids morphologically identical with those of the bleached strains. Upon exposure to light the proplastids enlarged and greened. In cells which grew under continuous light the plastid system appeared as an interconnected system of tubules. Cells maintained on a schedule of 12-hour light and 12-hour dark had plastids which were detached from each other.

Notes: SYNOPSIS. Euglena and Chlamydomonas were cultured in an organic medium in the dark and at several light intensities (15, 60 and 150 ft-c) at temperatures from 20d̀ to 35d̀C. Below 32.5d̀, growth of Euglena was independent of light. Chlamydomonas was light dependent at all temperatures where growth occurred; there was no growth in the dark, at 15 ft-c, or at temperatures above 32.5d̀. At 35d̀, growth of Euglena became inversely light dependent; the higher the illumination, the poorer the growth. Multinucleated, giant euglenas were found at 35d̀, a greater percent of abnormal cells appearing at the higher light intensities. Monsters were not observed in Chlamydomonas.To explain the growth-inhibiting, monster-inducing effect of elevated temperatures on Euglena, it is postulated that a dark-formed thermosensitive protein, essential for normal cell division, is denatured. Light may increase the effect of heat on chlorophyll and the chloroplast, possibly by being converted to intraplastidic heat through the plastid carotenoids, thus having some indirect synergistic role in the phenomenon.

Notes: SYNOPSIS. Erythromycin bleaches Euglena gracilis in a manner resembling that of streptomycin. Erythromycin-bleached substrains have been cultivated 16 months in light on erythro-mycin-free media without greening. Bleached substrains were obtained only if erythromycin was added to actively growing cultures: erythromycin did not bleach if added during the stationary phase of growth of green cultures.

Notes: SYNOPSIS. Conchophthirus curtus is a thigmotrich that occurs on the gills of Unionid clams (Elliptio complanatus in this study). The anterior third of the endoplasm, unlike the remainder, is relatively firm and without gastrioles; it contains an extensive aggregation of specialized endoplasmic granules and is therefore called granuloplasm. On the surface ventral to the granuloplasm is a thigmotactic area that bears closely set, strongly adherent cilia. There is no evidence that the granules are intracellular microorganisms; they are Feulgen-negative and do not divide, nor do they stain like bacteria. Cytochemical tests show that the granules contain neutral fat, fatty acid, phospholipid, glycogen, and mucin. The evidence indicates that the principal function of the granules and granuloplasm is the production of mucin, which is supplied to the underlying thigmotactic cilia, thereby conferring on them their adhesive properties. Thus, the granules and granuloplasm constitute a mucous organelle, and to the extent that they are osmiophilic and secretory they qualify as Golgi bodies and Golgi material, respectively. Since endoplasmic granule is a general term for any of the granules of protozoan endoplasm, it is recommended that the granules of the present study be called muciferous granules.

Notes: SYNOPSIS. This is a description of structures seen in EM preparations of the macronucleus of Paramecium aurelia, using both starved and growing organisms, the latter at timed stages after fission. The effects of treatment with RNA-ase, DNA-ase and of the “silver-Feulgen” reaction are described, and comparisons made between structures in the macronucleus and the micronucleus. The appearance of macronuclei in thin (2 μ) paraffin sections, stained by the Feulgen, azure A and pyroninmethyl green methods, and upon examination by ultra-violet micrography, is also considered. From these observations it is concluded that the macronucleus contains a large number of structures, 0.5 μ in diameter, consisting of an outer RNA-containing region and central elements containing DNA. These bodies, which are usually thought to be “nucleoli” by other workers, are now considered to be the most likely candidates for the genetic “sub-nuclei” which have been postulated from genetic work.

Notes: SYNOPSIS. The longitudinal kineties of the holotrich ciliate Trimyema marinum each bear only three widely spaced cilia; but these cilia are located at identical horizontal levels so that they comprise three helicoidal ciliary bands running around the anterior pole of the organism. The two kineties whose cilia are found most anteriorad, located in a right dorso-lateral position on the body, are exceptional, however: they are prolonged anteriorly, bearing numerous short additional cilia.These two “polykineties” wind clockwise around a kind of apical disc; their distal extremities continue to curve, dipping into a “prebuccal invagination” in which they may be said to constitute a vestibular ciliature.In spite of its rather unique characteristics, the curious anatomy of this ciliate does conform to the organizational type recognized for holotrichs of the order Trichostomatida.

Notes: SYNOPSIS. A number of small molecules including CO2, certain Krebs cycle acids and certain amino acids stimulated growth and glucose utilization of a colorless strain of Euglena gracilis in a phthalate-buffered mineral salts medium. Their major effect was to shorten markedly the lag period; some compounds also gave small increases in maximum growth rate and total cell yield. The stimulatory substances were effective in small (sparking) amounts. It is suggested that all the stimulatory substances acted similarly, by keeping the internal concentration of oxaloacetate at a sufficiently high level to allow effective operation of the terminal respiratory cycle.Glucose utilization was initiated within a pH range of 3.0 to 5.0. This range could be extended by the addition of glycine to the growth medium. Cells cultured at pH 4.5 could be adapted to growth at pH 7.0 in a phosphate-buffered mineral salts medium containing a small amount of citrate. Neither adaptation nor growth occurred at pH 7.0 in the absence of citrate. Since no evidence of citrate utilization was obtained and since EDTA replaced citrate, it is concluded that citrate was acting as a chelator.The major enzymes of the Embden-Meyerhof-Parnas and pentose phosphate pathways were demonstrated in cell-free extracts. The data presented indicate that glucose metabolism in Euglena is similar to that found in a wide variety of other cells. Indirect evidence was also obtained for the operation of a uridine linked pathway in hexose metabolism.With the exception of hexokinase, for which results were inconsistent, all the enzymes demonstrated were routinely found in the supernatant fraction of the cell-free extracts. The pH optima of a number of the enzymes were found to be between pH 7.5 and 8.6, although the cells from which the enzymes were obtained were grown in acid medium.

Notes: SYNOPSIS. Cannibal giant Blepharisma undulans americanus, NYU strain, grown in mass culture, showed increased numbers of macronuclear lobes and greater variability in their number, compared to the bacteria-fed form. Feulgen and methyl greenpyronin preparations stained both the DNA and RNA of the cannibals and of the ingested forms within the food vacuoles.During the first 3 to 6 hours of digestion, macronucleus and deoxyribonucleic acid disappear from the food vacuole; during the last 6 hours the ribonucleic acid disappears from the food vacuole; DNA and RNA are therefore presumed to be digested and absorbed.

Notes: SYNOPSIS. Production of a “vitamin B22-like compound” by Tetrahymena pyriformis mating type II, variety 1, and 3 other tetrahymenids was demonstrated. The compound produced by T. pyriformis was nutritionally active for Escherichia coli and Lactobacillus leichmannii and inert for Ochromonas malhamensis and Euglena gracilis, despite use of a variety of the standard methods for liberating bound B12. By dry-weight it is present in 1 part in 30 million. Its chromatographic and electrophoretic properties are described.

Notes: SYNOPSIS. Turnix suscitator (Galliformes), Phaenicophaeus javanicus (Cuculiformes), and two passerine birds, Dicaeum cruentatum and Pycnonotus dispar, harbor Plasmodium vaughani Novy and MacNeal in the States of Pahang, Perak and Trengganu. P. rouxi Sergent, Sergent and Catanei occurs in the same localities and in Kelantan too, in the following eight passerines: Chloropsis cyanopogon, Copsychus malabaricus, Geokichla sibirica, Malacocincla rostrata, Pitta megar-hyncha, Pomatorhinus hypoleucos, Pteruthius erythropterus and Pycnonotus goiavier. This is the first report of either parasite from Malaya, and from the hosts listed. Taxonomic criteria are discussed, and it is pointed out that Dr. A. H. Helmy Mohammed's “bow-tie” schizonts are a useful guide to the recognition of P. rouxi.

Notes: SYNOPSIS. A leptomonad flagellate found in large numbers in the latex of the asclepiad plant Pergularia extensa in East Africa has been identified as Phytomonas elmassiani (Migone). The flagellate is believed to undergo cyclical development in the lygaeid bug Oncopeltus famelicus which feeds on Pergularia. Following the ingestion of infected latex by the insect, the flagellates on reaching the midgut enter a growth phase and increase in size to form giant leptomonads. These probably then migrate to the salivary glands of the bug, possibly by boring through the gut wall, haemocoel and walls of the salivary glands. The salivary gland forms represent a multiplication phase in the life-cycle, and numerous small metacyclic forms are produced which are then injected into a plant host to initiate a new infection.Also infecting the midgut of Oncopeltus famelicus is another trypanosomatid, Blastocrithidia familiaris (Gibbs). It is characterised by the possession of an undulating membrane and the habit of budding off leishmania bodies from its anterior end.These bodies are resistant and serve in the transmission of the parasite from bug to bug.The two flagellates of Oncopeltus famelicus are readily distinguished from one another, not only on morphological grounds but also on their behaviour in vitro. B. familiaris can be cultivated on a monophasic glucose-peptone broth. It then loses its undulating membrane but retains its budding habit. Phytomonas elmassiani will not grow on this medium but when inoculated into a diphasic peptone blood-agar medium the latex forms will undergo development comparable to their insect midgut phase.The plant trypanosomatids appear to form a well-defined group bearing little similarity to the monogenetic insect flagellates of the “crithidia” type. It is suggested that the culture form Strigomonas (=Crithidia) oncopelti, allegedly parasitic in asclepiads and Oncopeltus fasciatus, might be simply an insect parasite, its original plant association being quite fortuitous.

Notes: SYNOPSIS. Ten- or 12-day cultures of Trypanosoma ranarum in Diamond's SNB-9 medium contain large numbers of slender crithidia and considerably smaller numbers of pear-shaped crithidia, but in fresh media the pear-shaped bodies constitute about 93% of the population after 5 days whereas slender forms make up about 4–5%; the remainder are leishman bodies. Succeeding days show a different cycle in that the slender forms increase to some 93% at 10–13 days and the pear bodies decrease to some 3% of the total at the same time.When washed in Krebs-Ringer phosphate buffer alone, neither morphological type shows endogenous respiration; in glucose containing buffer, O2 consumption becomes evident; pear-shaped crithidia use, on an average, 12.6 μl O2/hr/108 whereas slender forms utilize 17.7 μl O2/hr/108 parasites. Malonate at 0.01 m inhibits O2 consumption of slender forms about 61% as compared to 27% with the pear-shaped bodies. A speculative discussion of the relation between morphological types, O2 consumption in the presence of glucose, and malonate inhibition is presented.

Notes: SYNOPSIS. Short sections of deoxyribonucleic acid (DNA) in the elongated macronucleus of Euplotes eurystomus were labeled by means of a short exposure to tritiated (H3-) thymidine to follow by autoradiography the fate of the labeled DNA during amitotic reorganization of the macronucleus. During amitosis the radioactive DNA that was restricted during interphase to short sections of the nucleus is dispersed and becomes evenly distributed throughout each daughter macronucleus.Although the reorganization bands normally originate only at the ends of the macronucleus, additional bands can start at other places on the macronuclear surface. Bands of the same macronucleus originate with a high degree of synchrony. DNA synthesis is a constant feature of the rear zone of every reorganization band.

Notes: SYNOPSIS. Thin sections of Lankesterella garnhami were examined by electron microscope and the morphology of trophozoites and sporozoites is described. The envelope of the organism consists of a double membrane, which (in the presumed sporozoite) is broken at one point posteriorly by the microphyle. The anterior end possesses characteristic organelles, which include an open apical ring leading to a collar or conoid and to 30 peripheral fibrils, a paired organelle, and numerous “lankesterellonemes.” Typical mitochondria and a Golgi apparatus are found in the cytoplasm and a nucleus of heterogeneous nature.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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