Composition du suc de décongélation du muscle strié de la grenouille

Summary Because of cell membrane destruction, fluid escaping a muscle on thawing contains a large amount of proteins (myogen and globulin X). Whilst usual gradientsa, b, andc are present in the fluid, the gradientsd ande also occurring in extracts of unstimulated frog muscles are replaced by the gradientx already found in extracts of in N₂ exhausted muscles.     

Comparaison de l'activité respiratoire d'Esch. coli pendant la bactériolyse due aux bactériophages de la série T1 à T7

Summary The course of bacteriolysis as determinated by the oxygen consumption of the bacteria is different during bacteriolysis produced by the phagesT _1,3,5,7 as compared with that produced by phagesT _2,4,6. With phagesT _1,3,5,7, the bacteriolysis occurs, rapidly, but incompletely after a latent period. With the phagesT _2,4,6 bacteriolysis occurs slowly and the course of the respiration shows a « plateau » but goes to completion. The biochemical mechanism of the bacteriolysis therefore seems to differ in both cases.     

Photolyse ultraviolette et photoréactivation des bactéries — Aspects de dépolymérisation et repolymérisation des acides nucléiques bactériens

Summary Electrophoretic analysis of bacterial substance proves the departure, from UV irradiated microbes screened from light for a certain time, of substances which were responsible for increasing the charge density by surface unit during the first moments which follow the irradiation by UV rays. Spectrophotometric analysis of liquids having contained these bacilli proves concommitantly the diffusion of those substances from the bacterial substance to the aqueous phase and reveals their nature. The photoreactivity which is possible during the first moments following the UV irradiation of bacilli, due to the presence of the fragments of depolymerisation of nucleic acid macromolecule in the bacterial substance, becomes impossible after the departure (diffusion) of those fragments to the aqueous phase. These observations seem to show that the phenomenon of photo-reactivity is connected with the repolymerisation of the macromolecule primitively divided of desoxyribonucleic acid.     

L'action de l'hypoglycémie sur l'électrorétinogramme du lapin

Summary Hypoglycaemia in the rabbit due to an intravenous injection of insulin results in an important diminution of the value of theb wave in the ERG (up till 80%). Nevertheless, this phenomenon does not follow directly upon the lowering of the blood glucose level but takes place, on the average, about 2 h later. This fact is explained by the enormous energy reserves of the retina, the lowering of the ERG taking place only when these reserves are exhausted.

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Travail subventionné par la FondationEmil Barell (Bâle).     

Analyse expérimentale du développementin vitro des germes plumaires de l'embryon de poulet

Zusammenfassung Die Differenzierung der Dunen des Hühnerembryos lässt drei Phasen erkennen: 1. Eine der Haut fremde Anregung löst im Corium die Bildung der Dunenanlagen aus; 2. diese Dunenanlagen üben eine kurzfristige induzierende Wirkung aus, die die Epidermis zur Ausbuchtung der Dunen veranlasst; 3. die auswachsende Dunenepidermis kommt dann selber zur Induktionsaktivität und bewirkt das Eindringen der Coriumzellen in den in die Länge wachsenden Epidermiszylinder.     

Action du LiCl sur de jeunes blastodermes de poulet cultivésin vitro

Summary The young blastoderms cultivatedin vitro, by the method ofNew, slightly modified, grow abnormally on a medium of albumen mixed with LiCl solution. It acts in the first place upon the morphogenesis, secondarily upon the differentiation of organs, if they are able to develop.

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Travail subventionné par le Fonds national suisse de la Recherche scientifique.     

Activité staphylostatique de composés du groupe des benzophénarsazines

Summary It is shown that certain compounds belonging to the group of angular benzophenarsazines display a high specific bacteriostatic activity towardsMicrococcus pyogenes var.aureus. This biological property provides a further ground of similarity between these compounds and one of their structural analogues, 3,4–5,6-dibenzocarbazole.     

L'action du 2,4-dichlorophénoxyacétate de sodium sur les végétaux

Zusammenfassung 0,5prozentige Lösungen von 2,4-dichlorophenoxyessigsaurem Natrium verhindern das Keimen vonAgrostemma Githago, Hordeum vulgare undTriticum vulgare. Das Wachstum junger Pflanzen der drei Arten wird durch Verpflanzen auf mit 0,5prozentigen Lösungen dieses Stoffes getränktem Sand gehemmt. Schwächere Lösungen gestatten das Wachstum, es ist aber verlangsamt und die Pflanzen tragen Mißbildungen verschiedener Art, die an die nach Einwirkung von Colchicin und Heteroauxin beschriebenen erinnern. Stark verdünnte Lösungen (5·10^–6) beschleunigen das Wachstum und regen die Wurzelbildung an; diese Wirkung ist beiHordeum vulgare besonders deutlich.     

Présence d'uraninite dans les minéraux accessoires du granite de baveno

Summary Microscopic crystals of uraninite are found in the accessories of the Baveno granite by the nuclear photographic emulsion technique. The uraninite is believed to be a primary mineral of the granite, its concentration in the sample is less than 1 p.p.m. but it contributes about 10% of the total activity.     

La libération des deux acides nucléiques au cours de l'autolyse des bactéries et sa signification

Summary The existence of a process of directed mutation for aBacterium coli through the action of the desoxyribonucleic acid released by anotherBacterium coli during its autolysis raises the question of the behavior of the two sorts of nucleic acids during the autolytic desintegration of the bacterial cell. Working with several germs, we have seen that autolysis releases a nucleoproteidic fraction containing from 20 to 30 per cent of nucleic acid. The desoxyribonucleic acid represents 50 to 70 per cent of the total nucleic acid; this value is very much higher than that of the initial germs, which contain but 20 to 30 per cent. The signification of the easy mobilization of the desoxyribonucleic acid by autolysis is discussed, according to the observations made in usingRobinow's method of nuclear staining.     

Action d'un inhibiteur de la carboanhydrase,l'acétazolamide,sur l'excitabilité du cortex,du thalamus et du rhinencéphale

Summary The electrical activity induced by stimulation of the cortex, diencephalon and rhinencephalon was studied in the rabbit under the influence of a carbonic anhydrase inhibitor, acetazolamide or Diamox. A significant decrease of the excitability was found in the diencephalon.The rapidity and the electivity of this action, as well as the blood pH variations simultaneously registered, suggest a specific inhibition of cerebral carbonic anhydrase by Diamox, although a participation of the metabolic acidosis cannot be fully excluded.     

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.     

Action de la ribonucléase sur les cellules du carcinome d'Ehrlich

Summary The reduced form of ribonuclease acts on the cells ofEhrlich's carcinoma by producing important changes in the RNA content of cells:(1) First, there is an important synthesis of intracellular RNA and an accumulation of free nucleotides (from the external medium). This phenomenon accompanies the necrosis of the cells.(2) After this first stage begins a rapid degradation of intracellular RNA.Simultaneously, the respiration of cells decreases whilst protein content remains unchanged.The oxidized form of ribonuclease has no action on the cells.

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Aspirant du Fonds national belge de la Recherche scientifique.     

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.     

Effets comparés de laβ-propiolactone et du formol sur les propriétés inductrices de l'organisateur chez les amphibiens

Summary -propiolactone-treated dorsal lips ofAmbystoma mexicanum are grafted in the blastocele of young gastrulas. The inducing ability of dorsal lips is not altered. These results are compared with the effects of formaldehyde which suppress the inducing ability. An interpretation of these facts is proposed. The cross-linking reactions which occur between formaldehyde and proteins may be important for the suppressing of the inductive ability by this agent.     

Sur L'origine du ‘Principe Général’ de Jean Le Rond D'Alembert

This article intends to propose new hypotheses concerning the origin of the ‘Principe général’ of mechanics of Jean Le Rond D'Alembert expressed in its Traité de dynamique in 1743. The examination of the statics of Pierre Varignon and its inheritance suggests that D'Alembert retains, through a case of oblique collision on a hard surface, a method of decomposition and equilibrium of forces which is close to its principle. On the other hand, this principle requires a definition of the equilibrium widely spread in the 17th and 18th centuries, D'Alembert seeming then more to innovate from an epistemological point of view that on a technical one. Finally, the determination of rules of collision based at the same time on decompositions of movements at the level of the centre of mass and on appeal to a principle of relativity constitutes a know-how at the beginning of the 18th century which can be moved closer to methods developed by D'Alembert. These three aspects try then to replace the science of D'Alembert in a context by insisting on the essential role of the collisions of body and on that of the notion of equilibrium concerning the birth of its principle.     

L'influence de divers métabolites glucidiques sur l'intensité respiratoire du testicule de rat blanc

Zusammenfassung Glukose, Fruktose, Zitrat und Pyruvat erhöhenin vitro den Sauerstoffverbrauch des Rattenhodens; Saccharose ist wirkungslos.Glukose, Fruktose und Zitrat werden mit verschiedenen Geschwindigkeiten oxydiert, wobei dem Pyruvat eine katalytische Wirkung zukommt.     

Actions de la néostigmine,du D.F.P. et du 3318 CT sur la sensibilité du rectus de grenouille aux esters acétique,propionique et butyrique de la choline

Summary The potentiating effects of Neostigmine, D.F.P. and 3318 CT (a selective true cholinesterase inhibitor) on acetylcholine (ACh), propionylcholine (PrCh), butyrylcholine (BuCh) and amyltrimethylammonium (AmT), have been studied using the frog's rectus abdominis. Neostigmine increases the actions of the three esters much more than that of AmT. Low concentrations of D.F.P. potentiate maximally BuCh but have practically no effect on ACh, PrCh, and AmT. 3318 CT potentiates AcCh and PrCh but inhibits BuCh and AmT.These results indicate the specificity of the hydrolysis of pharmacologically active doses of BuCh, on the one hand, of AcCh and PrCh, on the other hand, by different enzymes or the frog's rectus.Results obtained with high concentrations of D.F.P. and with association of the different anticholinesterases indicate that a maximal or nearly maximal potentiation of one of these esters is already obtained with the specific inhibitor concerned; the supplementary inhibition of the non-specific enzymes thus appears to have no or only a poor effect.