ALBERT

Notes: Es wird bei Soja mit Hilfe der tagesperiodischen Blattbewegungen der Verlauf der endogenen Tagesrbytbmik unter Licht-Dunkel-Zyklen untersucht, die denen In Wareings Experimenten entsprechen.Bei den langen Dunkel-Periodeu zwischen 39–51 Stunden Dauer, die mit Haupt-Lichtperioden von 6 oder 9 Stunden alternieren, tritt etwa 20 Stunden nach deren Beginn eine Dunkelstarre ein. Die nächste Lichtperiode induziert erneut eine nicht mehr als etwa 30 Stunden andauenide Rhythmik, der dann wieder eine Dunkelstarre folgt.Störlicht von 30 Minuten Dauer hat während der Zeit, in der die Rhythmik läuft, einen relativ geringen Einfluß auf den Zeitpunkt von Hebung und Senkung. Wirkt es aber wäbrend der Dunkelstarre, so bedingl es ebenso wie eine Haupt-Lichtperiode einen neuen Start der endogenen Tagesrhythmik.Aus diesen Befunden lassen sich die Ergebnisse Wareings über die Wirkung des zu verschiedenen Zeiten der Duukelperiode gebotenen Störlichts erklären.

Notes: Euglena gracilis v. bacillaris and E. gracilis v. fuscopunctata produce the same three carotenoids, β-carotene, lutein and neoxanthin in approximately the same relative amounts. Lutein is the major pigment and β-carotene represents about 10–15% of the total. The concentration of carotenoids in E. gracilis v. bacillaris is very high, reaching 700 mg./100 g. dry weight.Streptomycin (0.02%, w/v) and darkness reduced growth of E. gracilis v. bacillaris by about 50% and carotenoid synthesis by about twenty times. Diphenylamine (1/70,000) reduced growth and carotenoid synthesis equally (about 50%). In no case was the synthesis of more saturated polyenes (the phytofluene series) stimulated.The nature of the eye spot pigment is discussed.

Notes: The infection of mice and baby rats by both Plasmodium lophurae, an avian parasite, and Plasmodium berghei, a mammalian malaria parasite, prompted investigation of the likelihood of P. berghei infecting avian erythrocytes. Though erythrocytes of chick embryos were not infected, those of the goose and duck embryos were. In both these cells the morphology of the parasite was markedly different from that seen in mammalian erythrocytes. Infections were transitory and it was impossible to find parasites after 4 days. Examination of the hosts of both species of parasites showed a rather wide range and examination of the susceptibility of the duck erythrocyte indicated that this cell was peculiarly receptive to infection by a variety of plasmodia.

Notes: Breeding colonies of protozoa-free laboratory rats (Rattus norvegicus) and golden hamsters (Mesocricetus auratus) were established by early weaning or by drug treatment. Attempts were made to transfaunate the enteric protozoa of various rodents to protozoa-free progeny of these colonies. Efforts to transfer the fauna of guinea pigs (Cavia porcellus) to rats and hamsters have failed and indicate that this fauna is physiologically isolated as well as morphologically distinct from that of other laboratory rodents. The faunas of rats and hamsters appear to be morphologically identical and freely interchangeable. That certain of the species found in rats and hamsters also occur in the mouse (Mus musculus) is indicated by successful transfaunations: mouse to rat and hamster. The suggestion is made that the fauna of the mouse and rat is indigenous but that the fauna of laboratory hamsters may have been acquired since domestication. Hexamastix muris from Neotoma fuscipes and Trichomonas microti from Microtus pennsylvanicus have been transfaunated to rats. Other enteric protozoa from these hosts and also from Marmota monax and Dipodomys merriami have not established themselves in rats and, if morphological differences cannot be found, should be considered biological races of their counterparts in the fauna of laboratory rodents.Species of lumen-dwelling enteric protozoa should be based upon morphological distinctions and not upon host specificity. The latter, as demonstrated by these experiments, is not rigidly determined.

Notes: About 3,000 clones of Astasia longa J, a colorless protozoan flagellate, were available for testing for biochemical mutations. Each clone was derived from a single flagellate which had been exposed to either ultraviolet or X-radiation and which had been cultured subsequent to irradiation in a complete medium. To test for biochemical mutations, an attempt was made to grow each clone in the minimal medium that suffices for the parent strain. Some clones were incapable of continuous growth in complete medium, others failed to grow or grew slowly in minimal medium, and still others grew abnormally in minimal medium when first tested but later reverted back to normal. These results are compared with those reported for various fungi and certain tentative conclusions made regarding gene mutations.

Notes: A new ciliate from the marine clam Mya arenaria is described and figured. The form is designated Trichodina myicola with specific characters as follows: Bell-shaped to discoidal; length 31–86 microns; diam. 62–103 microns; diam. denticulate ring 29–46 microns; 26–36 denticles; diam. of basal disk 42–79 microns; adoral ciliary spiral performs slightly more than one turn; posterior ciliature in three closely applied, concentric tiers: an anterior circlet of marginal cilia, a middle circlet of overlapping membranelles, and a posterior circlet of inner cilia; macronucleus C-shaped; micronucleus small, round, lying near outer curvature of left arm of macronucleus; large contractile vacuole present near end of left arm of macronucleus.Taxonomy in the genus Trichodina is discussed and outlined. Special attention is given to details of the oral ciliature. T. myicola is compared with other members of the genus. A checklist of Trichodina species is presented.

Notes: The feeding processes of Salenophrya micraster were studied and described in relation to the apparent selection of acceptable live prey ciliates, the feeding time in relation to the number of tentacles operative, and the contractile vacuole rate during feeding and subsequent reproduction. On the basis of these observations, the fundamental mechanisms involved in the suctorian feeding process are discussed.

Notes: The literature involving the genus Tetrahymena has become so voluminous in recent years that some consolidation of it appears advisable. Through 1953 well over 500 papers, scattered through more than 100 scientific journals, have been devoted in whole or in part to studies in which species and strains of this genus, under a variety of names, have been employed as one of the experimental animals. Nearly half of these works are cited directly in the present paper. The major areas of research in which these ciliates have been used to advantage include physiology and biochemistry, containing nearly 60% of all the papers, cytology and taxonomy, and three smaller fields arbitrarily designated as cytogenetics, morphogenesis, and parasitism. Tetrahymena's sustained popularity as an object of research may be considered as due primarily to its ability to thrive axenically in a chemically defined nutrient medium and secondarily to such factors as its ubiquity in nature, its ready adaptability to a variety of ecological situations (including endoparasitism), its possession of a relatively primitive and fundamental type of buccal ciliature of considerable phylogenetic significance, and its exhibition of the sexual phenomena of conjugation and autogamy.

Notes: A new sand-dwelling ciliate, Discotricha papillifera n.g., n.sp., is described and allocated to the trichostome family Trichopelmidae. The species seems to be one of the most highly differentiated members of the family. The peculiar type of its body ciliature and of its buccal structures suggests affinities with certain other major groups of ciliated protozoa; from an evolutionary point of view the organism appears to show close relationship to the gymnostome family Chlamydodontidae.

Notes: Antigens consisting of simple fractions of T. cruzi and L. donovani produced high titer antisera in the rabbit after a short immunization series. The antisera resulting from these immunizations showed several types of serologic reactions with the living antigens when the dark-field serial dilution technique, devised for these experiments, was employed.

Notes: Solenophrya micraster, originally collected from a strip mine pond in east-central Illinois, was established in clone cultures. From these homogeneous populations, detailed studies on the morphology and life cycle of the species were made. On the basis of the morphology established by these studies and a review of the species assigned to the genus by previous workers, emended diagnoses of genus Solenophrya Claparède and Lachmann 1859 and Solenophrya micraster Penard 1914 are proposed.

Notes: Five standard antimalarial drugs have been tested, in the present study, against trophozoite-induced Plasmodium hexamerium infections in ducks; namely, chloroquine, proguanil (paludrine), pyrimethamine (daraprim), pentaquine and isopentaquine. (Four others were used previously.) Two doses daily were given for a treatment period of 7 days. The effectiveness of treatment was measured in terms of its ability to suppress parasitemia and to completely prevent relapse (i.e. to achieve sterilization). Of the five drugs, the two pentaquines were about equally effective. They rapidly cleared the blood of parasites, and completely aborted the infection in nearly all cases. The other three drugs failed to sterilize any of the cases treated, and were not even effective as suppressants.The pentaquines, however, proved quite toxic to the host and, even in the dosages used, retarded the normal rate of weight gain. Pyrimethamine had a similar effect, and in addition interfered with normal feathering. Neither of these effects, whether due to pentaquines or pyrimethamine, was recovered from after treatment stopped.

Notes: New investigations of the nuclear cycle in the gymnostome ciliate Loxodes rostrum verify the long-neglected hypothesis proposed by Bütschli that in this multinucleated ciliate the macronuclei never divide. The consequences of this “caryosterose” are compensated for by a process of endomixis, that is, by the transformation of a certain number of the micronuclei, during vegetative multiplication, into new macronuclei.The nuclear cycle in the gymnostome Centrophorella fistulosa does not show any aspect of nuclear division. Interpretation of this supposes the existence of polyenergid nuclei which fragment, during the interdivisional period, into subnuclei; among these some evolve in the somatic and macronuclear direction, before disappearance by karyolysis; others, corresponding to the micronuclei, grow by endomitosis, and reconstitute the polyploid and polyenergid nuclei. Thus the very particular nuclear cycle of C. fistulosa is believed to exhibit a new aspect in the endomictic process of nuclear reorganization.

Notes: A simple, rapid method of staining the external organelles of hypotrichous ciliates is described. Specimens are fixed and stained with Noland's combined phenol-formaldehyde, gentian violet fixative and stain. The staining solution is displaced with iodized glycerine as soon as the external structures are stained to prevent it from coloring the cell body. Cirri and membranelles are stained jet black in sharp contrast to the clear amber background.

Notes: The results of these studies indicate that the first diatom flora developed at the 13-meter level. The flora at 12 meters increased. At the 11- and 9-meter levels the lake became increasingly eutrophic. Both plankton and benthic forms were present. At the 8- and 7-meter levels the lake was in a transitional stage from lake to bog conditions. From 6 meters to the surface bog conditions were present.

Notes: Mass cultures of a stock of Paramecium polycaryum maintained over a period of several years showed abundant and frequent nuclear reorganization stages resembling those of ex-conjugant and ex-autogamous animals of other species of Paramecium. Conjugation has never been reported for P. polycaryum, nor has it been found in these studies. Cytological examination of stained preparations revealed a process of autogamy in P. polycaryum, closely similar to that described previously for P. aurelia. As a rule, all four of the micronuclei, the typical vegetative number in P. polycaryum, engage in the first prezygotic division which is characterized by the formation of prophase crescents. Variable numbers of the eight nuclei continue with the second division. A maximum of sixteen nuclei may result. Apparently, only one of these normally completes the third prezygotic division to form the gametic nuclei, although more than one may initiate it. A fusion nucleus (synkaryon) arises in, or near, a paroral cone, thus paralleling autogamy in P. aurelia. A series of postzygotic divisions produces eight definitive nuclei, four of which become macronuclear anlagen and four remain micronuclei. The first division of the synkaryon results, possibly, in the formation of a viable nucleus and a non-viable one, as in ex-conjugants of P. caudatum. After the last micronuclear division, a skein evolves from the old macronucleus which has become flattened and leaf-like. The skein rapidly segments into “sausages” which transform into spherical fragments, about thirty in number. Two cell divisions restore the normal vegetative nuclear complex.

Notes: An account is given of the spontaneous occurrence and prolonged maintenance of strains of Trypanosoma evansi devoid of the kinetoplast. The structure and nature of this organelle—which is regarded as a plastid—are discussed and previous work on its loss is reviewed. Among the six akinetoplastic strains studied, two were kept under continuous observation for about 17 years, in the course of which many thousands of trypanosomes were examined, without a single normal flagellate being detected. In these cases, therefore, the aberrant condition had become permanently fixed as a heritable character. Another strain of T. evansi first exhibited considerable fluctuation in the number of akinetoplastic forms (1–70%) but subsequently reverted to the normal state. The perpetuation of the akinetoplastic condition appears to be due to failure of the kinetoplast to divide, with the result that trypanosomes thus incapacitated divide irregularly, giving rise to akinetoplastic forms, which continue to breed true. This may lead to the production, on the one hand, of fluctuating strains, in which the akinetoplastic and normal trypanosomes compete for survival; and, on the other hand, of totally akinetoplastic strains. The loss of the kinetoplast is comparable to the loss of plastids in phytoflagellates. In a discussion of the genetic aspects of this phenomenon it is regarded as a mutation determined by plastogenes, for the mutant trypanosomes appear suddenly, breed true, and give rise to a new race. Moreover, the kinetoplast once lost does not arise de novo. It is suggested that T. equinum had originated from an akinetoplastic strain of T. evansi produced by such mutation.

Notes: Two problems were posed for experimental analysis: (1) What is the effect of omission of both conjugation and autogamy on fission rate and other characteristics of P. aurelia? (2) What effects does autogamy have when it occurs after intervals of varying length since the last previous fertilization? These questions were explored most thoroughly in stock R of variety 1 and stock W of variety 2; but some data are also presented for stocks S and 60 of variety 1, stock E of variety 2, and stocks 29, 32, 47, and 51 of variety 4 and their hybrids. In essential features the results on all stocks and varieties are in agreement, as far as they go; but the details differ.To the first question, the answer is simple and clear: under the conditions of culture employed, fission rate declines and death eventually occurs in daily isolation lines that omit both conjugation and autogamy. The maximum number of fissions until death was about 350 in stock R (variety 1), about 300 in stock W (variety 2) and perhaps as low as 200 in variety 4. Early in life the fission rate is high and shows little or no decrease for a considerable time; it then decreases progressively and slowly for a long time; and may finally decline at a faster rate. Decline and death are preventable by permitting autogamy to occur repeatedly without unduly long intervals between them. Viable lines maintaining high fission rate may be continued in this way without apparent limit.The answer to the second question is more complex, for autogamy may have any one of several consequences. Even in controls undergoing recurrent autogamy at relatively short intervals, autogamy sometimes yields nonviable clones or clones with low fission rate; but it usually yields viable clones manifesting normal high fission rate. Likewise, the most vigorous clones arising at autogamy from parents that have not begun to decline in fission rate show no increase in fission rate, but undergo a whole life cycle consisting of as many fissions as the total life cycle of the parent from its origin at fertilization until its death. As the parents progressively decline in fission rate, the most vigorous clones to which they give rise at autogamy again initiate new life cycles characterized at the start by normal high fission rate. Since the latter is above the fission rate level of the parent, rejuvenescence is at once apparent.However, not all autogamous offspring of aging parents initiate new life cycles at the normal maximum fission rate level. Some exhibit an immediate marked decrease in fission rate below the level of the controls and the parents and may maintain about the same fission rate for long periods. Others drop at once to low fission rate and appear to start to decline further very soon. Still others show very little or no change from the level of the parental fission rate, even when the latter has declined greatly at the time of their origin. Variation in the fission rate of offspring arising at autogamy is one of the capital facts brought out by this study. Rejuvenescence at autogamy occurs, but only in some autogamous offspring.At the other extreme, autogamy in aging clones—as in controls—sometimes leads to death at once or within several fissions. The frequency with which this happens increases markedly with the age of the parent and eventually it becomes impossible to obtain viable autogamous offspring, as also reported by other investigators. At this stage in the life history, the doom of the strain is sealed: it will die eventually without autogamy and it will die quickly if it undergoes autogamy. Finally, in the last stage of the life cycle, autogamy can be induced only with difficulty and in a small proportion of the animals, if at all.Yet, in spite of all the risks involved, the animals must undergo autogamy (or conjugation) or perish. Of those that take the risk, if they have not waited too long to do so, some will survive and be rejuvenated. The end result of our study is thus to place on a firm experimental basis the conclusion to which Woodruff and Erdmann (47) were forced forty years ago by the logic of the situation, even in the absence of experimental analysis: conjugation is not essential for P. aurelia; autogamy (endomixis) alone can maintain the organisms in life and vigor.The main hypotheses that have been advanced to account for senescence and rejuvenescence in ciliates are discussed in the light of the foregoing results and other available knowledge. It is concluded that present information does not yet permit a decision as to the correct interpretation. Certain values and difficulties of the various hypotheses are pointed out, as are some opportunities to bring recent advances in knowledge to bear decisively on a choice among them. It appears possible that the ultimate solution of these problems will involve elements of more than one of the current hypotheses.

Notes: Forty species of fresh and brackish water protozoa collected on August 3, 1947, on Penikese Island in Buzzards Bay, Massachusetts are identified and listed. A short historical account of the expedition on which the collection was made is given together with a brief description of the ecology of the Island. The bibliography is a nearly complete record of all published papers of the fauna and flora of Penikese Island.

Notes: Unstable micronuclear behavior was investigated in an unusual race of Paramecium caudatum. Lines were begun, after isolating single vegetative specimens, to yield mass cultures. After study of living specimens in the precision micro-compression chamber and permanent preparations stained with Feulgen and iron-hematoxylin, most paramecia revealed a single micronucleus but many were observed with two micronuclei and fewer with more than two micronuclei—occasionally three, rarely four. Specimens measured 225 microns in length; the micronucleus about seven microns. Instead of normal cyclosis, the protoplasm exhibited great fluidity. Generally two contractile vacuoles were present but specimens with three vacuoles, even four, were not uncommon.The method of producing amicronucleate specimens and those with variable numbers of micronuclei was discovered by studying large numbers of actively dividing paramecia. Instead of a micronucleus passing to each daughter at the end of fission as in normal animals, the entire late telophase stage of the dividing micronucleus is passed to the anterior or posterior daughter cell at the time of constriction of the cell. The result is that one daughter is bimicronucleate and the other daughter amicronucleate. Bimicronucleate and amicronucleate animals are capable of dividing normally. In bimicronucleate specimens, division stages show two micronuclei in late telophase stages that result in four micronuclei, two passing to each daughter cell. However, aberrations may again occur in fission to produce variations in number of micronuclei. The irregularly shaped, atypical, macronucleus may extrude chromatin or may undergo complete fragmentation (hemixis, type D). Paramecia and macronuclei may be parasitized by a microorganism which may cause this derangement of normal micronuclear events. This possibility of induction of micronuclear variation in Paramecium by foreign microorganisms may be of considerable evolutionary significance in the genus.

Notes: Views on the nature of the cytoplasmic fibrils which occur in Lophomonas striata are considered. It is concluded that on the basis of available information the rods or fibrils should be considered as structures characteristic of this flagellate.

Notes: The effects of ethanol on conjugation and division in Paramecium caudatum were studied in six concentrations ranging from 0.001M to 0.5M, over a period of 72 hours.A marked increase in the number of conjugants was noted in concentrations between 0.001M and 0.05M alcohol, especially during the first 48 hours of exposure. The optimum concentration for conjugation was 0.005M at which there were 439% more conjugants than in the control.Division also increased in the same alcohol concentrations that caused increase in conjugation. The optimum concentration for division was 0.005M. This stimulating effect of alcohol on division reached its peak within the first 24 hours.

Notes: Growth of Tetrahymena pyriformis in a peptone medium is inhibited slightly to extensively by comparable concentrations of oxalate, citrate, and ethylenediaminetetraacetic acid (in ascending order). Single additions of Ca, Cu, Zn, and Mg, in increasing order of effectiveness, reversed citrate inhibition. EDTA inhibition was completely reversed by single additions of Ca or of certain other metals (Al, Co, Cu, Fe, Mn, Ni, Zn) forming more stable EDTA complexes. Reversal by added Mg was slight. The data suggest physiological importance of Ca for T. pyriformis.Pre-treatment of peptone solution with a cation exchanger (Natrinil) resulted in little or no growth; growth was restored almost to normal by the addition of Mg. The growth-response showed a linear relationship to quantity of Mg.

Notes: Of 165 sea urchins (Strongylocentrotus dröbachiensis) examined in the Mt. Desert Island region, 41 harbored the intestinal ciliate Plagiopyla minuta in considerable numbers. Division in this ciliate is clean; i.e. it is not accompanied by the visible elimination of macronuclear material. Long periods (probably several weeks) of vegetative life appear to alternate with brief periods of intense divisional activity in P. minuta. Twenty-five of these same urchins also contained in their digestive tracts a species of Euplotes which was identified as E. balteatus. This hypotrich was also found commonly in the region as a free-living organism. Dividing specimens were found regularly in the urchin, and such specimens showed the usual macronuclear reorganization which occurs in Euplotes and its near relatives. The evidence indicates that E. balteatus is a facultative commensal, which is perhaps now in the process of acquiring the endozoic habit.

Notes: The complete synthetic medium for the growth of Tetrahymena pyriformis E was subjected to gamma-radiation from cobalt60. A dose-response curve indicated the range of radiation which damaged the medium so that growth of Tetrahymena was inhibited.The essential vitamins and amino acids which comprise the medium were individually irradiated in solution. Media were prepared with single irradiated components and tested for their ability to support growth of the protozoa.Thiamine, riboflavin, pantothenate, pyridoxine, folic acid, and thioctic acid were destroyed by less than 1 × 106 rep, while 2 × 106 rep was required to inactivate nicotinic acid. Most amino acids proved to be relatively radiation-resistant. At the high radiation levels of 1 × 107 rep and 2.3 × 107 rep respectively, only serine and methionine were damaged. All other amino acids remained biologically active even after receiving 2.3 × 107 rep, the highest level of radiation employed. Organoleptic observations, however, showed radiation-caused color and odor changes in many of those amino acids whose biological activity for Tetrahymena was unaffected. The nucleotide, guanylic acid, was also inactivated at 2.3 × 107 rep.

Notes: Cell-free extracts of Tetrahymena pyriformis S synthesize citrulline from ornithine, and arginine from citrulline. The extracts also show arginase activity.Urease activity at various pH values has maxima at both pH 5.6 and 7.4. This points to two distinct enzymes. The presence of urea in ciliate cultures during early stages of growth, and its absence during the stationary phase of cultures, correlate with the shift in pH of the culture media and with the activity of the “alkaline” urease at various pH values.

Notes: An astomatous holotrichous ciliate inhabiting the excretory tubule of the freshwater gastropod Ferrissia peninsulae is believed to be conspecific with Dogielella renalis Kay, found originally in the renal organ of an unidentified species of another pulmonate genus, Physa. The organization of the ciliary system and the arrangement of the contractile vacuole pores suggest that it is closely related to members of the hymenostomatous genus Tetrahymena, and that it has evolved from a ciliate of this general type through loss of the cytostome and cytostomal membranelles.Because it is not possible at present to state with certainty that this ciliate is congeneric with D. sphaerii, the genotype of the genus Dogielella Poljanskij, a new genus, Curimostoma, is established for it. Curimostoma is referred provisionally to the family Tetrahymenidae.

Notes: Tetrahymena [Paraglaucoma] rostrata (Kahl, 1926) Corliss, 1952 occurs commonly in litter and occasionally in soil. It has previously been recorded from moss. In nature it feeds on cytolyzed or moribund tissue, but feeds on bacteria and flagellates in the presence of peptone. It is a facultative parasite of enchytraeid worms which it infects through degenerate setal follicles. It may also infect accidentally injured worms. The ciliates are attracted by histolysis and by peptone. Resistant cysts are formed regularly in the absence of food and encystment appears to be accelerated by crowding. Excystment is readily obtained with hypotonic salt solution. Theront, trophont, tomont and tomite stages are recognizable in the life cycle. Conjugation has never been observed.

Notes: The extracellular development of Plasmodium lophurae in vitro was favored by the addition, to the erythrocyte-extract medium, of a coenzyme A (CoA) preparation of about 75% purity. The effect of CoA was the same regardless of the concentration of free pantothenate in the medium, indicating that the parasites require the complete coenzyme rather than its pantothenic acid moiety. Erythrocyte extracts were found to contain enzymes which hydrolyzed added CoA at a rate such that 8 units per ml. of coenzyme was only slightly destroyed after 3 hours’incubation but almost completely destroyed after 18 hours’incubation at 40°C. The CoA content of erythrocytes from chickens or ducks heavily infected with P. lophurae was about twice as high as that of erythrocytes from uninfected birds. The increased CoA was associated with the parasites, an observation suggesting that malaria parasites can accumulate this essential growth factor which they cannot synthesize. The CoA concentration in the livers of infected chickens was approximately 40% lower than that in the livers of control chickens. The livers of ducks on the 6th day of infection had a slightly lower CoA concentration than those of uninfected ducks. This depletion in CoA, together with the depletion in biotin previously demonstrated in P. lophurae infection, may play a role in the pathology of this infection.

Notes: Amacronucleated single animals of Paramecium aurelia are produced by a three-step procedure. The three steps are: 1) the formation of homopolar double animals, 2) the reduction in number of macronuclei from two to one and the maintenance of this unimacronucleated condition, and 3) the occurrence of clefts in these unimacronucleated double animals. The amacronu-cleated single animals are produced from the unimacronucleated, partially separated, homopolar double animals either by fission or by the complete separation of the two components of the double animals. The method described may apply in principle to many other ciliates.

Notes: The position of the contractile vacuoles in non-dividing Paramecium aurelia, as judged by that of the pores, is relatively constant both laterally and longitudinally, as is the distance between them. Some variability of the distance between the pores persists from the recent fission among the smaller animals of normal shape. At the onset of fission two new vacuoles appear, one anterior to each of the old vacuoles; all the vacuoles must undergo relocation because their mean positions now are somewhat removed from that in the non-dividing animals. The pores of the front daughter are too close together: the anterior pore is too far back, and the posterior is too far forward; likewise the pores of the hind daughter are too close together: the anterior too far forward as well as the posterior. The relocation does not begin until shortly before separation of the daughters and is practically complete by the time the daughters have assumed their normal length/width ratio after separation. A neuroneme connects the pore to one of the basal granules adjacent to its place of origin, now far removed.Occasionally more than one new pore appears at the usual time and place during very early fission; these are very close together and usually serve a single vacuole. However, most of them fail to survive the relocation following this and the next fission, so they are found in the posterior position very rarely. But, in some individuals they may survive and serve a single or separate vacuoles. In a certain clone of Paramecium aurelia multiple pores and vacuoles are rather frequent; these are, of course, the result of the tendency to produce multiple pores and vacuoles at the time of fission.

Notes: Leucocytozoon marchouxi is described from the mourning dove, Zenaidura macroura carolinensis in Illinois. The macrogametocytes are rounded or elliptical, measuring 7 to 11 by 8 to 15 microns (mean, 9 by 12 microns), and stain dark blue with Giemsa stain. The microgametocytes are often distorted or ruptured by the smearing process, but if not badly injured measure 5 to 11 by 8 to 15 microns, (mean, 8 by 11 microns). They stain pale blue with Giemsa stain. Host cell cytoplasm is rarely seen surrounding the microgametocytes, but was found in 26% of cells parasitized by the macrogametocytes. When present it forms a narrow border around part or all of the parasite's periphery, and is not drawn out to form elongate “horns.”The parasite was found in ten birds, of which five were adults, one was a juvenile, and four were nestlings. The infections were relatively light in the adults. The youngest bird in which the protozoon was found was 14 days old.The literature on Leucocytozoon in the avian order Columbiformes is reviewed. All forms with rounded gametocytes so far reported are considered to be L. marchouxi Mathis and Leger, 1910, of which L. turtur Covaleda Ortega and Gallego Berenguer, 1946, is considered a synonym.

Notes: Strains of Colpoda maupasi previously reported were found to produce only octogenic reproductive cysts and monogenic wrinkled resting cysts. The present form of C. maupasi (Bensonhurst strain), isolated by the senior author in 1949, was found to produce, in addition to the above, quadrigenic reproductive cysts, digenic corrugated (wrinkled) resting cysts, and smooth thick-walled monogenic, digenic and quadrigenic resting cysts. Some of the factors leading to the development of these cysts in the Bensonhurst strain are believed to be related to nutrition, age and size of the trophic forms. The cytological changes in encystment and excystment were followed with particular attention to aging monogenic resting cysts. The latter were observed for over 4 years.

Notes: Tests based on respirometric and population growth methods for the analysis of oxidizable substrates for Chilomonas paramecium revealed that only those substances tested which are intermediates in terminal cyclic respiratory mechanisms (pyruvate, lactate, acetate, α-ketoglutarate, succinate, fumarate, L-malate, oxalacetate, but not citrate, cis-aconitate or DL-isocitrate) were attacked. These organic acids, and the fatty acids and alcohols earlier known to be used, n-butyric, n-caproic and n-caprylic acids, ethyl, n-butyl and n-hexyl alcohols, were the only carbon compounds oxidized by C. paramecium under the test conditions employed.Utilization of acid substrates was found to be pH-dependent. Reproductive and respiratory rates were related to the pKa values of the compounds. Oxidation of acetate, lactate, and pyruvate, however, was observed at pH values where their molecular form was present in exceedingly small amounts.Naturally-occurring α-amino acids, amines, glycolysis intermediates (3-phosphoglyceric acid, glucose-1-phosphate, hexose diphosphate) and degraded intermediates of glycolysis (glyceric acid, glycerol, dihydroxyacetone, glucose), two-carbon compounds more oxidized than acetic acid (oxalic, glycolic, glyoxylic acids, glyoxal, ethylene glycol), and formic, tartaric, malonic, and glutaric acids, were not used.Respiration in the presence of single members of the group of oxidizable substrates was sensitive to malonate and fluoroacetate. Malonate inhibition of succinate oxidation could be reversed by an increase in succinate concentration, but the relationship was not competitive; possibly because of permeability differences between the substrate and inhibitor. Fluoroacetate inhibition was accompanied by the accumulation of citric acid.The experiments on substrate oxidation, and the effects of inhibitors on the respiratory metabolism of the flagellate, are considered to provide evidence for the operation of the Krebs tricarboxylic acid cycle as a terminal respiratory mechanism in C. paramecium.

Notes: Using two different stocks of P. caudatum and four of P. multimicronucleatum it was observed (total of 25 cases) that starved fragments do not regenerate either end of the cell up to the time of death though they survived long past the time required by feeding fragments to regenerate. Fragments which were prevented from regenerating by an initial period of starvation later regenerated when supplied with nourishment (69 cases). Only three fragments failed to recover normal form when fed, two showing conspicuous abnormality instead and one remaining unable to feed. Short anterior fragments (32 cases) and posterior fragments (four cases) which are nucleate but do not include the feeding organelles can neither feed nor regenerate either normal body shape or the oral structures. In seven cases it was found that when the oral region of whole animals was injured they could no longer feed and in six of these cases no mouth or gullet could be found. It is therefore suggested that organelles of ingestion cannot be regenerated when excised or damaged even though the normal site be present. These observations are considered to demonstrate that regeneration in Paramecium is entirely different in type from that of most protozoa in that it occurs only through feeding and subsequent growth if ingestive organs are already present in part at least. It does not occur by the remodeling of body shape, with the formation of oral primordia derived from more general cytoplasmic differentiations, as is the case in most ciliates. The original surprise of Balbiani in finding that his fragments of Paramecium did not regenerate like other ciliates is now explained.

Notes: [Auszug] THE report of the Royal Observatory, Cape of Good Hope*, for 1952, which has recently become available, shows that it was "a reasonably satisfactory" year for the Observatory. The weather, from the point of view of observing, was well above average during the first part of the winter, and good ...

Notes: [Auszug] IN two United Nations publications, "European Timber Trends and Prospects"* and "European Timber Statistics, 1913-1950"t, the Food and Agriculture Organization of the United Nations has summarized information collected jointly by it and the Timber Committee of the Economic Commission of Europe ...

Notes: [Auszug] Fig. 1. Projection on (001) of the density of neutron scattering due to hydrogen atoms in potassium dihydrogen phosphate at - 180 C. Contours are drawn at intervals of 50 units. Broken lines are negative contours and the zero contour is shown dotted ; no positive contours appear. The small circles ...

Notes: [Auszug] When the number of showers occurring in half-hourly intervals of sidereal time is averaged over the year, the figures show a sidereal variation with first Fourier amplitude 1-06 ± 0-16 per cent with the maximum at 19-3 ± 0-6 hr. local sidereal time. This result is similar to the ...

Notes: [Auszug] In the flux equation, the influence of net solvent-flow can be expressed as an additive flux term equal to the velocity of water-flow times the concentration of the component studied at the membrane point considered1. The integration of the general equation describing the simultaneous operation of ...

Notes: [Auszug] Reference will be made here to (per cent) 'prob-ability of blackout' rather than to storm-Z) regions. Diurnal variation of blackout probability is determined by counting the number of instances (at each hour for the four-year period) of excessive absorption. In these cases the letter B is the ...

Notes: [Auszug] This suggested to me that it might be worth while to attempt to reduce the dielectric losses in steatite, forsterite and other ceramics by a prolonged heat treatment at a temperature well below the firing temperature of the ceramics. The heat treatment was chosen quite arbitrarily as 60 hr. at ...

Notes: [Auszug] In the only case where an enzyme has been separated from a crude extract by the use of a column of 'IRC 50'2, the enzyme studied seems to be the only one to be adsorbed on the resin, while most of the other proteins pass right through the column. The fact that proteins often are not adsorbed on ...

Notes: [Auszug] (1) Section, 50 n thick, of a mucus-secreting salivary gland from a 190-gm rat injected intraperitoneally 4 hr. previously with sodium sulphate labelled with sulphur-35 (approx. 2 c of sulphur-35 per gm. body-weight). Hsema-toxylin and eosin. (2) Corresponding contact radioautograph. Both x 80. (3) ...

Notes: [Auszug] When handling a paper, a person may leave his fingerprints on it, depending on many factors such as physiological conditions, time of contact between the fingers and the paper and other unpredictable circumstances. A spontaneous fingerprint contains 98-5-99-5 per cent water, the rest being organic ...

Notes: [Auszug] We had previously considered this possibility, but had rejected it because the RF values of the unidentified amino-acid in phenol and butanol - acetic acid were appreciably different from the values reported for sarcosine in the literature2'3 and because it did not give the colour test with ...

Notes: [Auszug] THE following arrangements have been made for Royal Society Lectures during 1954 : Leeuwenhoek Lecture, by Prof. J. H. Quastel, professor of biochemistry, McGill University, Montreal, and director of the Research Institute, Montreal General Hospital, on "Soil Metabolism" (May 6) ; Croonian Lecture, ...

Notes: [Auszug] THE essay subjects for this year's Endeavour prizes of the British Association for the Advancement of Science will be as follows : the upper atmosphere ; heat of the earth ; coal as a raw material; water supply ; the span of life ; and colour photography. Essays must be sent in by June 1 and must ...

Notes: [Auszug] NEW moon occurs on March 5d. 03h. llm., TJ.T., and full moon on March 19d. 12h. 42m. The following conjunctions with the moon take place : March lid. 13h., Jupiter 3 S. ; March 23d. 02h., Saturn 8 N. ; March 26d. 15h., Mars 3 N. Mercury is in inferior conjunction on March 1, after which it is a ...

Notes: [Auszug] In the communication "Pigmentation of the Jellyfish, Pelagia noctiluca"(Nature, January 23, p. 169, par. 7, lines 8 and 9, for "but no pyrrole reaction on roasting' read "and a pyrrole reaction on ...

Notes: [Auszug] THE Atomic Energy Research Establishment at Harwell is responsible for research into all the problems of atomic energy except those relating to atomic weapons, which are studied at the Armament Research Establishment under Sir William Penney at Aldermaston. The work at Harwell is mainly applied ...

Notes: [Auszug] A SYMPOSIUM on microradiography and auto-radiography was held on December 17, 1953, at the Institute of Physics, 47 Belgrave Square, London, by the Scientific and Technical Group of the Royal Photographic Society. Many modern scientific methods are intimately connected with photographic techniques, ...

Notes: [Auszug] THE thirty-sixth anniversary meeting of the Bose JL Institute took place on November 30, 1953, when Dr. N. K. Bose, director, River Research Institute, delivered the sixteenth Acharya Jagadish Chandra Bose Memorial Lecture on "The Role of Silt and Sand in Multipurpose River Valley Projects". Dr. ...

Notes: [Auszug] THE Forestry Commission Census Reports, Nos. 1 and 2, dealing respectively with the woods less than and more than five acres in extent (the latter including hedgerow and park timber) have already been reviewed in Nature (August 8, p. 240, and October 3, p. 616), and they have now been supplemented ...

Notes: [Auszug] THE occurrence in phenylhydrazine (Ph.NH.NHa) poisoning of a haemolytic anaemia with Heinz inclusion bodies in the erythrocytes is well known. Such inclusions also form rapidly in normal erythrocytes on in vitro incubation at 37 with phenylhydrazine1. With destromatized oxyhaemoglobin solution and ...

Notes: [Auszug] THE fundamental structural pattern of the periodic table of the elements is a network composed of two sets of lines corresponding respectively to periods and groups. This network is the result of the transformation of the linear array of. elements, arranged in order of their atomic numbers into a ...

Notes: [Auszug] IN northern temperate climates, a serious problem in maize cultivation is that the growing season is usually too short to allow the grain to ripen1. It is therefore desirable to plant as early as possible. However, early plantings seldom give a good stand because in the germination phase the grains ...

Notes: [Auszug] The existence of a point A at which the rates of transformation of p to a and of y to a are equal raises the interesting question as to whether there is a transition point between p- and y-sulphur at or near this temperature. This possibility is suggested by the following considerations. In certain ...

Notes: [Auszug] Early experiments designed to determine the rate of secretion of milk did not allow for variations in the amount of this residual milk, and it was assumed that the yield of milk obtained at a milking was a true measure of the amount secreted since the last milking. These experiments8'4 indicated ...

Notes: [Auszug] To throw light on the subject, breast milks from four groups of mothers have been investigated: (1) Urban Bantu mothers in poor circumstances whose consumption of maize meal (90-100 per cent extraction) exceeded 1 lb. per diem, and supplied 65-85 per cent of total calories ; (2) Indian and ...

Notes: [Auszug] In a typical experiment, 0-6 gm. Worthington crystalline pepsin is dissolved in 60 ml. 0-1 M sodium acetate buffer of pH 5-6. The solution is then incubated at 37 C. and 10-ml. samples are withdrawn at intervals of 12, 18, 24, 30, 36 and 48 hr. and quickly chilled to 5 C. A portion of each sample ...

Notes: [Auszug] It seems that an example is furnished by some of the work carried out under the Colonial Research Council*. Under that Council is a committee dealing with insecticides which met first in January 1947. Since the report for 1948-49, that Committee has referred each year to experiments being done ...

Notes: [Auszug] (Meetings marked with an asterisk * are open to the public) Monday, March I ROYAL SOCIETY OP EDINBURGH (at 24 George Street, Edinburgh), at 4.30 p.m.-Prof. James Kendall, F.R.S.: "Humphry Davy and his Connections with Scotland". SOCIETY OF ENGINEERS (in the Apartments of the Geological ...

Notes: [Auszug] APPLICATIONS are invited for the following appointments on or before the dates mentioned: ASSISTANT LECTURER IN PHYSICS, and an ASSISTANT LECTURER IN THEORETICAL PHYSICS-The Registrar, King's College, Strand, London, W.C.2 (March 6). PRINCIPAL OF ERITH TECHNICAL COLLEGE-The Clerk to the ...

Notes: [Auszug] IN recent years it has been increasingly recognized that the research associations in Great Britain have an important part to play in technical and technological education. In part this arises out of the greater emphasis which has been placed on their function of securing the greater utilization by ...

Notes: [Auszug] PROBLEMS associated with "Industrial Methods of Sterilization" were discussed on January 13 at a symposium meeting in London organized jointly by the Society for Applied Bacteriology and the Microbiology Group of the Society of Chemical Industry. The first speaker, Dr. M. Ingram (Cambridge), ...

Notes: [Auszug] PROF. ROBERT WILLIAM WHELDON died on January 15, shortly after collapsing in his office in the School of Agriculture, King's College, Newcastle upon Tyne. His death is a severe loss to the University of Durham and to the many agricultural interests with which he was connected. He was widely known ...

Notes: [Auszug] DR. HANS BENNDORF, professor emeritus of physics in the University of Graz, Austria, died on February 11, 1953. He was born in 1870 at Zurich and was the son of the well-known archaeologist, Otto Benndorf. He studied mainly in Vienna, and he was appointed lecturer in the University there in 1899. ...

Notes: [Auszug] WE regret to announce the following deaths : Mr. A. Campbell, one of the original members of the staff of the National Physical Laboratory, on February 6, aged ninety-one. Prof. Kotaro Honda, formerly of the Tohoku Imperial University, known for his work on magnetism and in metallurgy, on ...

Notes: [Auszug] DR. RALPH ALEXANDER RAPHAEL has been appointed to the recently created professorship in organic chemistry in The Queen's University, Belfast. Part of Dr. Raphael's schooldays were spent at Wesley College, Dublin. He graduated from the Imperial College of Science and Technology, London, in 1941 with ...

Notes: [Auszug] DR. K. S. DODDS, who has been appointed director of the John Innes Horticultural Institution, Bay-fordbury, Herts, in succession to Prof. C. I). Darlington, is a botanist with wide knowledge of economic plants and particular interests in the field of cytogenetics bearing on their evolution. After ...

Notes: [Auszug] THE Prize Committee of the American Association for the Advancement of Science announced during the recent annual meeting that the twenty-sixth Newcomb Cleveland Prize of 1,000 dollars had been awarded to Prof. Barry Commoner for his paper entitled "Studies on the Biosynthesis of Tobacco Mosaic ...

Notes: [Auszug] THE report of the Director of Water Pollution Research and that of the Water Pollution Research Board are contained in an interesting publication entitled "Water Pollution Research 1952"*. It is not possible in a short notice to indicate all the interesting work that is being done on this ...

Notes: [Auszug] IN a comprehensive anatomical investigation of the aleurone layer in the cultivated barley, J. Sawicki (Polska Akademia Umiejetnosci,"No. 66, 1-59, pub. Krakow, 1952, with English summary) has examined 103 varieties, representing all the sub-species of Hordeum sativum collected in different parts ...

Notes: [Auszug] IN a small illustrated pamphlet entitled "The Forestry Commission in Scotland" (recently published by the Forestry Commission) it is stated that the history of forestry in Scotland is a long one. Shakespeare in "Macbeth", for example, brought the Birnam Woods to Dunsinane, a difficult military ...

Notes: [Auszug] THERE is evidence that zinc is necessary for animals and plants; but information about the physiological role of this metal is scant. The enzyme csCrbonic anhydrase, present in red blood cells and certain other tissues, contains zinc as an integral part of the protein molecule1; but little is known ...

Notes: [Auszug] IN a previous communication1 it was shown that the atomic masses of various chemical elements can be calculated with precision by means of the pykno-X-ray method, when the density and X-ray data of the crystalline solid have been measured at the same temperature. It is to be noted, however, that ...

Notes: [Auszug] 8-AZAGUANINE, which differs from guanine in having the carbon atom at position 8 replaced by nitrogen, inhibits the growth of certain bacteria, fungi, algae, protozoa, animal tumours, and some plant and animal viruses. Some evidence'has been presented1 that, in certain of these cases, 8-azaguanine ...

Notes: [Auszug] In Drosophila melanogaster, genie interaction has been demonstrated in the determination of antigenic specificity, a finding difficult to reconcile with the one gene - one protein hypothesis. In one series of isogenic stocks, interaction between at least three non-allelic loci is responsible for ...

Notes: [Auszug] An interesting demonstration of the penetration of stream water into the sub-surface gravel was obtained by burying ripe ova, obtained by stripping a female trout, in the mound of gravel in the experimental tank, some 4 ft. distant from the inflow. A dilute suspension of spermatozoa from a ripe ...

Notes: [Auszug] This problem has been investigated on a macroscopic scale, with lumps of coal and smooth weathered stones, 4-8 cm. in size. It was found that the best measure of height is given by SsinQ, where 6 is the shadow angle and S is the distance from the mid-length of a particle, measured in the direction ...

Notes: [Auszug] To minimize interference with a nearby ionospheric recorder working on 5-8 Mc./s., efforts were made to reduce the noise generation. A shunt capacity of 0 1 (JLF. was found to be effective; but its effect on the ultra-violet spectrum was marked. Fig. 1 shows two recordings of the spectrum of the ...

Notes: [Auszug] THOUGH each monograph written by the holder A of a George Fisher Baker Non-Resident Lectureship in Chemistry at Cornell University is an eagerly awaited scientific publication, Prof. C. K. Ingold's volume arouses special interest, since it is a large and fully referenced treatise which gives the ...

Notes: [Auszug] THE first volume of Dr. C. E. Raven's Gifford Lectures contains a survey of the work of the early naturalists, of its relation to other scientific studies and to the general climate of thought. This historical survey is made for a theological purpose. For Dr. Raven, 'natural theology' and 'natural ...

Notes: [Auszug] THE title of Prof. Haupt's new book, while admittedly correct, is perhaps rather misleading, and plant taxonomy might have been a more appropriate title. It is a survey of the principal groups of the plant kingdom, all of which are dealt with from the point of view of structure, reproduction and ...

Notes: [Auszug] THE extreme diversity among the algae has A presented a compelling challenge to the development of classical phycology based primarily upon studies of morphology, life-history, taxonomy and ecology. A few algae have been selected for the physiological study of cellular processes such as ...

Notes: [Auszug] ON February 6, Mr. Cecil Warburton celebrated his hundredth birthday. Mr. Warburton entered Christ's College, Cambridge, in 1876. He became a demonstrator in the School of Agriculture and in the Department of Zoology in the University, and later he was a member of the Quick Laboratory which ...

Notes: [Auszug] IF fats are to be produced by the industrial utilization of moulds, cheap carbon sources such as cellulose waste and molasses must be considered. As sucrose is the major constituent of molasses, the first stage in the relevant investigations is to ascertain the behaviour of different moulds towards ...

Notes: [Auszug] RESEARCH on the problems of marsupial reproduction is at present in progress in this department. Several marsupial species are housed in the departmental enclosures; but so far systematic work, here briefly reported, has been limited to the Rottnest Island wallaby (Setonix brachyurus Quoy and ...

Notes: [Auszug] THE nature of lattice defects in neutron-irradiated diamond is a problem of current interest. These defects are known to cause changes in some of the physical properties1 and give rise to a paramagnetic absorption spectrum. We have measured this spectrum in the temperature-range 20-290 K., using ...

Notes: [Auszug] RECENT comparative and experimental studies of leaf morphology have aroused a renewed interest in the relationship between leaves and buds. In the fern Dryopteris aristata, Wardlaw1'2 has shown that bud and leaf primordia are histologically identical, and that buds may be caused to develop at ...

Notes: [Auszug] The only answer I can find to the last question is this. Let rjci - 0 be the distance between the and the Ith carbon nucleus (k I). Let F be a symmetric function of the n (n - l)/2 variables r#, the value of F being equal to the biggest of its arguments. (This does not contradict its symmetry ; for ...