Aspects biochimiques de la Régénération

Summary A survey of the biochemistry of regenerating animals has been made: after a critical discussion ofChild's metabolic gradients theory, the relative importance of respiration rate, carbohydrates, proteins and nucleic acids metabolism are stressed. The similarities between biochemical processes in the embryo and the regenerating organism are pointed out.

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Une grande partie de cet article est la reproduction d'un chapitre de notre livre « Embryologie chimique » (Masson, Paris, etDesoer, Liége); nous tenons à remercier les éditeurs de l'ouvrage qui ont bien voulu marquer leur accord. On y trouvera une bibliographie étendue sur les modifications chimiques dont l'organisme en régénération est le siège.     

Étude quantitative de la régénération caudale,avec ou sans moelle épinière,chez la larve de Salamandre

Summary Tail regeneration in the absence of spinal cord was studied quantitatively in larval salamanders. Growth parameters were calculated according to the function =1/ny _i /x _i (Rao).The regeneration rate of despinalized tails was found to be approximatively half the normal rate in both the length and volume.The real nature of despinalized tail regenerates is discussed and two hypotheses are proposed for their explanation.

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Travail exécuté grâce une subvention de la «DonationGeorges etAntoine Claraz, instituta et curataJohannis Schinz professoris auspiciis».     

Les états de la matière dans la pétrogénèse profonde

Sans résumé     

Les états de la matière dans la pétrogénèse profonde

Sans résuméDoyen de la Faculté des sciences de Besançon.     

Mise en évidence d'une nouvelle forme combinée de l'acide glutamique dans le latex d'Euphorbia characias L

Summary The hydro-alcoholic extract ofEuphorbia characias Latex contains one unknown amino acid and one new combined form of glutamic acid, isolated by preparative electrophoresis on cellulose powder.

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Nous exprimons nos remerciements à Mrs. les ProfesseursBoulanger etG. Biserte pour les conseils reçus au cours de ce travail.     

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.     

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.     

L'introuvable révolution scientifique. Francesco Redi et la génération spontanée

The Italian naturalist F. Redi established in 1668 that insects are not produced by the way of equivocal generation, contrary to what was affirmed since the Antiquity. For that reason, many historians of sciences acknowledge his experiments, like those of Galileo, Boyle or Huygens, contributed to the scientific revolution that emerges in the seventeenth century in Western Europe. Based on the commentaries sparked off by the works of Redi, in his time and today, our contribution shows on the contrary that nothing at all in his approach reveals such an intention. Questioning without arrogance the knowledge and the authority of the Ancients, careful interrogation of the literariness of the Scriptures, adoption of an experimental reasoning still dependent on the scholastic argumentation, those are the main characteristics of his work. But those also could be the ones of Harvey, Borelli or Swammerdam's works. To defend the idea of a scientific revolution in the life sciences similar in its conditions and tempo to the one described in the history of the physical sciences would be a mistake, not to say an anachronism.     

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.     

Importance des modifications de la glycémie dans la régulation de la vitesse d'absorption de solutions de glucose de différentes concentrations chez l'animal intact

Summary In intact guinea-pigs fed with glucose solutions of different concentrations, the main limiting factor of absorption is not the gastric emptying but the hyperglycaemia.     

Disparition de la 5-hydroxytryptamine dans les granulations des glandes de la peau deDiscoglossus pictus et deRana temporaria après injection de réserpine

Summary 30 min after an intraperitoneal injection of reserpine (5 or 10 mg/kg) in the frog (Rana temporaria) and in the toad (Discoglossus pictus), a substance which has the properties of 5-hydroxytryptamine (argentaffine reaction, azoreaction, indoreaction and fluorescence in U.V. after formaldehyde) disappears from the skin glands; the histochemical reactions are more positive again 1 1/2 to 2 h after the injection of reserpine.     

L'effet de la basse température sur l'incorporation de précurseurs des acides nucléiques et des protéines dans les cellules du méristème radiculaire deVicia faba

Summary The uptake of labelled RNA and protein precursors inVicia faba root meristems into nuclei at 4°C is less depressed than in the cytoplasm. Reversion of the normal pattern of incorporation would seem to indicate an inhibition of the RNA transfer from nucleus to cytoplasm.     

Principes généraux de la magnétochimie,ses applications à l'étude des structures

Summary This article presents the general principles of magnetochemistry, its methods and the results to which it leads. Firstly, the definitions of magnetic units of isotropic substances are defined. Then the main apparatus for measuring magnetic susceptibilities is indicated.The notion of a magneto-chemical system is developed and its use in the study of molecular structure is shown. Finally, the author shows how magnetochemistry has been used to study the electronic delocalisation in aromatic molecules, and the concomitance existing between this delocalization and the biological properties of certain substances, such as their mitotic and carcinogenic activities.     

Varignon ou la théorie du mouvement des projectiles ‘comprise en une Proposition générale

Cet article a pour objet de montrer la nouveauté du traitement varignonien du mouvement des projectiles dans les milieux résistants par rapport au traitement de ce problème présenté entre autres par Newton dans les Principia. Aussi, après avoir analysé cursivement différentes Propositions du Livre II des Principia, nous étudierons plus spécialement, dans les Mémoires présentés par Varignon à l'Académie Royale des Sciences entre 1707 et 1711, la mise en place de l'expression d'une ‘Proposition générale’. Nous montrerons ensuite sur quelques cas particuliers en quel sens on peut dire que l'étude du mouvement des projectiles dans les milieux résistants se réduit alors, pour l'essentiel, à de simples questions d'intégration et de différentiation.     

Application de l'analyse discriminante à l'étude des différences anthropométriques selon les groupes sanguins du système ABO

Summary Anthropological measurements on 193 Swiss recruits have been studied using discriminatory analysis. Out of the 9 characters measured on each individual, 3 were chosen to ascertain whether differences between the ABO blood groups exist. Discriminatory analysis gives a simultaneous evaluation of the differences of the 3 measurements. They are found not to be significant.     

Le rôle de l'hétérosis dans la compétition entreebony et son allèle normal

Summary Whereas in homozygous state the geneebony noticeably diminishes the sexual activity of the males, it can on the contrary increase it in heterozygous state; but this heterotic effect depends in a large measure on the direction of the crossing, and also on the genic and cytoplasmic context. It depends moreover on the temperature.The role of this activity in the populations whereebony is made to compete with its normal allel is discussed briefly.