Hundert Jahre Schweizer-Reagens

Summary Cuprammonia as a solvent for cellulose was discovered a hundred years ago byEduard Schweizer, Professor of Chemistry at the University of Zurich, and the heterogeneous swelling of plant fibres with this reagent was described in the same year byCarl Cramer, Professor of Botany at the Swiss Federal Institute of Technology then recently founded. Both discoveries were published in the Vierteljahrsschrift der Naturforschenden Gesellschaft Zürich 1857 and early 1858.     

Prevention of the formation of mycotoxins in whole wheat bread by citric acid and lactic acid (Mycotoxins in foodstuffs. IX)

Summary Additions of citric acid and lactic acid to whole wheat bread suppress the formation of aflatoxins byAspergillus parasiticus (0.5% citric acid, 0.75% lactic acid) and that of sterigmatocystin byA. versicolor (0.25 and 0.5% respectively).Acknowledgment. I thank Dr.R. Orth (Bundesforschungsanstalt für Ernährung, Karlsruhe, BRD) for the strain ofAspergillus versicolor.     

Regulation of tryptophan metabolism in the parasitic wasp,Habrobracon juglandis

Zusammenfassung Die Metabolite und 3 Enzyme des Tryptophanstoffwechsels vonHabrobracon weisen während der parasitären Phase sowie während der Puppenruhe und im Imaginalstadium signifikante Konzentrations-bzw. Aktivitätsveränderungen auf. Diese sind das Ergebnis mindestens zweier Regulationsmechanismen.

---

---

I thank Prof.V. Schwartz and Prof.A. Egelhaaf for helpful advice.     

Variations de la différence de potentiel électrochimique des chlorures chezNitella en présence de benzène sulphonate

Summary The chloride electrochemical potential difference between the inside of cells ofNitella translucens and some external solutions, where Cl has been progressively replaced by benzenesulphonate, has been measured by means of Ag-AgCl electrodes. It appears that benzenesulphonate moves into the cell by an electrogenic pump and that the uptake of Cl byNitella is not in contradiction with a carrier hypothesis.

---

---

This work was supported by grants from the F.N.R.S. and was carried out in the Biophysics Section of the Edinburgh University. We are indebted to Dr. E. J.Williams and Dr.Hogg for having sponsored this research and kindly provided the material.     

Adrenal relationships to aggressiveness in isolated female mice

Résumé Lorsque des souris femelles soumises à l'isolement sont groupées selon leur tempérament belliquex et non-belliqueux, on observe une augmentation de l'activité médullossurrénalienne chez les animaux isolés belliquex. Au contraire, les souris isolées non-belliqueuses ont montré des taux de catécholamines inférieurs et une secrétion cortico-surrénale nettement augmentée.

---

---

Submitted byRalph Schwartz to the faculty of Richard L. Connelly College, Long Island University in partial fulfillment of the requirements for the Degree of Masters of Science.     

Die Reizschwelle der Sinnesorgane als physikalisches Problem

Summary A survey is given of recent work on physical aspects of sensory processes. The reasoning which leads to the generally recognized view that one rod of the retina is excited by only one quantum of light is given in par. II. In par. IIIa summary is given of the papers byHecht andVan der Velden on the number of rods which must be struck in order to obtaina sensation of light. Par. III describes the role of the quantum character of light at higher intensities (de Vries), where it sets a limit to intensity discrimination and visual acuity. The influence of Brownian movement on the process of hearing is discussed in par. VI. It is found that the Brownian movement of the inner ear is close to the threshold actually observed (de Vries), whereas the Brownian motion of the air at the eardrum (seeSivian andWhite) is below the audible threshold. The role of the Brownian movementin the sense cells is described in par. VII; the results are used for an analysis of the mechanism of hearing (see alsode Vries); evidence is obtained that electric voltages are generated in the tectorial membrane (the well-known cochlear microphonics) and that they play an important part in the mechanism of energy transfer to the sense cells (similar voltages were also derived from the cupolæ in the lateral lines of fishes by the present author). Finally some physical arguments are sumarized againstYeagley's theory of bird navigation.     

Antibody against purified viper neurotoxin

Résumé L'anticorps contre la neurotoxine du venin deVipera palestinae est obtenu chez des lapins par immunisation de la neurotoxine purifiée liée à la cellulose carbométhylique.

---

---

This work is part of a thesis submitted byN. Shaham to the

---

This work is part of a thesis submitted byN. Shaham to the

---

This work is part of a thesis submitted byN. Shaham to the

---

This work is part of a thesis submitted byN. Shaham to the

---

This work is part of a thesis submitted byN. Shaham to the     

Effets d'analogues du chloramphénicol sur la différenciation de l'∄uf de l'oursinParacentrotus lividus

Summary The effects ofl-threo-chloramphenicol and thiophenicol on the differentiation of sea-urchin eggs are compared with those exerted byd-threo-chloramphenicol. Onlyd-threo-chloramphenicol caused vegetalization;l-threo-chloramphenicol inhibited development. These effects resemble those of nitrobenzene. Thiophenicol, differing fromd-threo-chloramphenicol by replacing the nitro group with a methylsulphonyl group, slows down development at high concentrations. The effects of chloramphenicol on oxidative phosphorylation and synthesis of proteins are discussed. It is suggested that both the steric configuration typed-threo of the side chain and the presence of a nitro group are necessary for the vegetalizing activity.     

Heinrich Hertz's laboratory notes of 1887

Communicated by Jed Z. Buchwald     

Hirngrössenvariation imFelis silvestris-Kreis

Summary The absolute and relative braincase capacity was described in the literature as one of the best criteria for distinguishing skulls of European wild cats (Felis silvestris silvestris) and domestic cats (Felis silvestris f. catus). Now it is shown that wild cats of North Africa (Felis silvestris lybica) and South Asia (Felis silvestris ornata), in contrast to the wild cats of Europe and of other parts of Africa, have likewise smaller brain capacities comparable to those of the domestic cat originating in this subspecies group ofFelis silvestris. This gives new evidence for discussing the theory of supposed considerable reduction of the brain size in domestication advocated especially byHerre and his collaborators, the general validity of which is called in question.     

Obtention,par la méthode des greffes de gonades embryonnaires,d'une femelle à descendance unisexuée femelle,chez le TritonPleurodeles waltlii Michah.

Summary Thanks to a method established byHumphrey ³ inAmbystoma sp. and founded on the orthotopic transplantation of the lateral mesoderm corresponding to the gonad primordium, we have produced, in the SalamanderPleurodeles waltlii Michah., 1 female which gives rise uniquely to female individuals. In this species, it is also possible to obtain, by an oestrogenic treatment during the larval stages of development, neo-females, these are genetic males feminized into phenotypic and perfectly functional females and their offsprings are uniquely composed of males². The ability to experiment at will with unisexual, male or female, offsprings allows us to attack from a new basis, before any perceptible gonadic sex differentiation, the analysis of the mechanisms of this differentiation in the SalamanderPleurodeles waltlii Michah.     

Chebyshev's lectures on the theory of probability

Communicated by B. Bru     

Gauss's first argument for least squares

Communicated by C. Truesdell     

A. A. Markov's work on probability

Communicated by H. Freudenthal     

Historical development of the Chinese remainder theorem

Communicated by C. Truesdell     

“Eratosthenes' measurement of the earth reconsidered”

Communicated by C. Wilson     

Ptolemy's maps of earth and the heavens: A new interpretation

Communicated by A. Aaboe     

The early history of the factorial function

Communicated by U. Bottazzini     

Kepler's hypothesis vicaria

Communicated by C. Wilson     

Newton's early computational method for dynamics

On December 13, 1679Newton sent a letter toHooke on orbital motion for central forces, which contains a drawing showing an orbit for a constant value of the force. This letter is of great importance, because it reveals the state ofNewton's development of dynamics at that time. Since the first publication of this letter in 1929,Newton's method of constructing this orbit has remained a puzzle particularly because he apparently made a considerable error in the angle between successive apogees of this orbit. In fact, it is shown here thatNewton's implicitcomputation of this orbit is quite good, and that the error in the angle is due mainly toan error of drawing in joining two segments of the oribit, whichNewton related by areflection symmetry. In addition, in the letterNewton describes quite correctly the geometrical nature of orbits under the action of central forces (accelerations) which increase with decreasing distance from the center. An iterative computational method to evaluate orbits for central forces is described, which is based onNewton's mathematical development of the concept of curvature started in 1664. This method accounts very well for the orbit obtained byNewton for a constant central force, and it gives convergent results even for forces which diverge at the center, which are discussed correctly inNewton's letterwithout usingKepler's law of areas.Newton found the relation of this law to general central forces only after his correspondence withHooke. The curvature method leads to an equation of motion whichNewton could have solvedanalytically to find that motion on a conic section with a radial force directed towards a focus implies an inverse square force, and that motion on a logarithmic spiral implies an inverse cube force.