Action de l'orientation et de la qualité de la lumière sur le développement des protonémas de Bryales

Summary The radiations coming from Blanc Brillant de Luxe' fluorescent stimulate the growth and ramification of protonema ofCeratodon purpureus (Hedw.) Brid. This stimulation is caused by red light (660 nm). Multidirectional lightening is more favorable than unidirectional exposition.     

Etude du remplacement catalytique du brome par l'hydrogène en présence du Ni-Raney

Summary We have just seen that the major course of a substitution reaction is determined by the nature of the groups already attached to the anthraquinone ring. The fact that pure members of the anthraquinone series may be readily prepared by catalytical dehalogenation, in the presence of Ni Raney under pressure at elevated temperature, is established. The fact that factors influencing the replacement of bromine by hydrogen are substituted groups in the para position is emphasized. These catalytic reductions are indicative of the peculiar effect of a substituted group on another atom or group in the para position.     

Recherches sur le mécanisme de la rétraction du caillot et de la métamorphose visqueuse des plaquettes

Summary The concept, that viscous metamorphosis of platelets and clot retraction is initiated by thrombin and a dialyzable factor was confirmed. Under certain circumstances glucose acts as dialyzable factor. Clot retraction seems to depend upon the catabolism of glucose.     

Influences des modifications simultanées de la concentration en ions K et Ca du liquide céphalorachidien sur le système vasomoteur

Summary In dogs anæsthetized with morphine-chloralosane, the cerebral ventricles are perfused with artificial solutions. After having been warmed up to body temperature, these solutions are allowed to flow into a lateral ventricle by a needle inserted laterally through the skull, the outflow taking place through a second needle placed suboccipitally in the cisterna. An excess of potassium in the cerebral ventricles increases the vasomotor tonus and the vasomotor responses produced by faradization of the central end of the vagus in the neck and by changing the pressure in the isolated carotid sinuses. An excess of calcium depresses the tonus of the vasomotor center and its reflex responses. An excess of calcium may be neutralized by an excess of potassium. Perfusion with a solution containing no calcium increases the tonus and the responses of the vasomotor center, while the absence of potassium does not seem to have any influence on the vasomotor system. A solution without potassium and calcium produces an increase of the tonus and the responses of the vasomotor center, these effects being due to the absence of calcium.     

Action répressive de l'oxygène sur la biosynthèse de la fumarique-réductase d'Aerobacter aerogenes

Summary The cells obtained from anaerobic cultures ofA. aerogenes contain both a hydrogenase and a fumaric reductase, but lack one or several electron transporters necessary for the coupling of the two enzymes. It is possible to measure the fumaric reductase activity of the extracts in the presence of hydrogen, hydrogenase and benzyl viologen, using the Warburg manometric technique. In anaerobic cultures the reductase is an inducible enzyme. In aerobic cultures its formation is strongly repressed by atmospheric oxygen.     

Etude de la consommation d'oxygène et de la teneur en acide désoxyribonucléique du foie à divers âges chez le rat

Summary The quantitative study of whole liver DNA and liver nuclei DNA at various ages, and the simultaneous study of oxygen uptake shows the following facts:(1) The rate of oxygen consumption to the fresh weight or to the DNA or to diploid chromosomes group is the same for the adult or the young aged 8 days. The values of oxygen consumption calculated for one cell or for one nucleus (taking notice of the fact that the mean level of liver nuclei DNA varies with the age) at 8 days is only the half of the adult value. Even at two months the value is 20% lower than in the adult.(2) In older animals there is a decrease of oxygen uptake which is more noticeable on a cellular scale than with the classical rate to fresh or dry weight. We affirm the fact that the diminution of the oxygen uptake of each cell is compensated by the increase of the number of cells.     

Activation concomitante par l'hétéroauxine de la résorption du corps paranucléaire ribonucléique et de la germination des zygotes chezAllomyces

Summary Heteroauxin (optimal concentration 10^–5) activates the germination of the zygotes and the dissolution of their RNA nuclear cap inAllomyces javanicus.Alkaline phosphatase has been located cytochemically in the cytoplasm surrounding the RNA nuclear cap.These new observations lead the author to postulate a relationship between the stimulating action of heteroauxin, activation of the phosphatases and awakening of the RNA-protein synthesis dynamic system during the germination of the zygotes inAllomyces.     

L'action du chlorure de lithium et du sulfocyanure de sodium sur la viscosité de la nucléohistone et des extraits d'embryons d'Amphibiens

Summary (1) LiCl increases the viscosity and decreases the rigidity of nucleohistone; NaSCN has opposite effects.(2) The effects of LiCl and NaSCN on the viscosity of amphibian embryo extracts, as observed byRanzi and his coworkers, seem to be due to the action of these salts on nucleohistone.     

Effet du fluoroacétate et des rayons X sur la teneur en acide citrique du foie de la souris

Summary In contrast to rats, male mice injected with sodium fluoroacetate accumulate citrate in their livers, whereas females do not. Whole-body irradiation reduces the level of accumulated citrate in the liver as well as in other tissues of the mouse.     

Influence de l'anaérobiose et de différentes tensions d'oxygène sur la libération d'histamine dans la réaction anaphylactiquein vitro

Summary The influence of anaerobiose and of varied oxygen tensions upon respiration and histamine release during anaphylactic reaction in guineapig lung slicesin vitro was studied.No histamine was liberated in the absence of oxygen. With increasing oxygen tensions, increasing histamine quantities were released; these quantities reached the control values when the atmosphere contained 10% oxygen.These results indicate that the mechanism of histamine release in the anaphylactic reaction is linked with the aerobic metabolism of the cell.

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Boursicrs du Consclho Nacional de Pesquisas.     

Quelques conceptions de la théorie des proportions dans des traités de la seconde moitié du dix septième siècle

This article examines how the theory of proportions was explained during the second half of the seventeenth century in the works of Andreas Tacquet, Antoine Arnauld, Ignace Gaston Pardies, Bernard Lamy, and Jacques Rohault. These five authors had very different conceptions of this subject, and on one hand, they show that this question was not forgotten, even after the Geometry of Descartes, and on the other hand, their work displays the progressive transformation of mathematical objects. While Tacquet deepened Euclidean thought, the others stopped taking the Euclidean model as paradigmatic and tried to change the order of the Elements and to establish book V of Euclid in new ways. We shall see that this multiplicity of the approaches highlights both the vitality of the reflections and the difficulty in developing a new ontology of mathematics. Some of them nevertheless opened new perspectives that were to bloom only much later. We shall also see the increasingly important place of the algebra as time went by.     

Le degré de polymérisation de l'amylose,de l'amylopectine et du glycogène

Summary A colorimetric method based on the reducing power of the aldehydic end group has been developed in order to determine the M. W. of polysaccharides. It has been found that corn amylose contains chain molecules of much higher degree of polymerization than potato amylose.     

Action de la triéthylènemélamie sur les mitoses de segmentation de l'œuf de Pleurodèle

Summary Triethylenemelamine (1/400 to 1/12000) induces pseudo-chiasmas and chromosome-breakage in the egg-segmentation mitoses ofPleurodeles waltlii Michah. The primitive effect is stickiness, breakages appear subsequently, but without an interval of time between: the primary physiological and the secondary genetical effect cannot be separated. There are points of breakability, which explains the symmetry of certain fragments. The action is inverted in the epidermal cells of the larvae, where spindle alterations are prominent. Cytodieresis is never inhibited.     

Spécificité de l'antigène tumoral décelé dans le foie de rat porteur d'une tumeur de Walker

Summary By means of systematic comparative immunoelectrophoretic analysis, it has been shown that the antigenic material appearing in the liver of a Walker tumour bearing rat is highly specific to the tumour. In fact we have been unable to detect such an antigen either in embryonic neonatal, regenerating or in the liver of acute inflammations bearing rats.

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Travail subventionné par l'Institut du Cancer du Canada.     

Traitement de la syphilis expérimentale du Lapin par la pénicilline en suspension dans l'huile

Summary When suspended in beeswax-peanut oil according toRomansky andRittman, a total amount of 50,000 Oxford units of C. S. C. penicillin (Commercial Solvents Corporation U.S.A.) pro kg., covering 8 intramuscular injections with intervals of one day, apparently sufficed to cure of syphilis (Ghent strain) rabbits infected into both testicles for two months to one year. The criteria of healing were applied 4 to 7 months after the end of the treatment and consisted in the transfer of the popliteal lymph nodes and other organs and in a second inoculation with the homologous strain. Unknown factors must be considered to explain the different results of the sole penicillinotherapy of syphilis observed in rabbits and in man.     

Influence de laβ-mercaptoéthylamine sur la réponse de l'intestin grêle du rat à une irradiation rœntgénienne localisée

Summary Intra-peritoneal injections of 15 mg of B-mercaptoethylamine in rats, with an average weight of 200 g, protect the small intestine against a local irradiation of 500 r on the antero-upper portion of the abdomen.This protection is proved mainly, as compared with the control, by a smaller decrease of cells still in mitosis after 12 and 24 hours and of the migrant cells in resting stage, by a greater precocity and higher quantitative value of the post-radiation normal and subnormal mitotic processes, and by variations in the mitotic formula (namely, in protected animals, a relatively high increase in the amount of metaphases).These experiments seem to prove a certain local and immediate action of the radio-protector, whose effects are not solely limited to the preparation of the generating system of the intestine for the later complete repair of the digestive epithelium.

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(Travail du Centre anticancéreux de l'Université de Liège et du Centre national belge pour l'étude de la croissance normale et pathologique).     

Influence de l'aneuploïdie sur la différenciation protéique au cours du développement embryonnaire de l'UrodèlePleurodeles waltlii Michah

Summary No qualitative differences have been found between the electrophoretic protein patterns observed in normal and in aneuploid embryos ( 3n × 2n). The overall amount of extractable protein increases, however, less rapidly in aneuploid than in normal embryos.     

Étude sur le choc produit par le polysaccharide du bacille du colon chez le rat porteur de tumeur (Note préliminaire)

Summary Aged preparations of polysaccharide fromE. coli were highly effective in inducing a lethal shock in rats bearing a tumor. This effect may be increased by some medications, while various steroid hormones afforded an efficient protection.