Zur Feinstruktur der materno-fetalen Verbindung im Placentom des Schafes (Ovis aries L.)

Summary The placenta of sheep is epithelio-chorial like those of cows and deer.     

Zur Evolution der Geschlechtsbestimmung beiCylisticus convexus (Deg.) (Crust. Isop.)

Summary In two strains ofC. convexus, an Isopod which is known to be sex-determined by a polygenic system, monofactorial sex determination has been found. This is considered to be the result of an evolutionary step from polygenic to gonosomal sex determination within the species.     

Zur Frage des Angriffspunktes des Thiouracil

Summary The mechanism of action of thiouracil and thiourea was investigated on Xenopus tadpoles. Both substances are able to stop metamorphotic changes if administered early enough. Characteristic disturbances occur in the epithelium of the thyroid follicles after only 24 hours. The action of these substances over a period of several weeks may lead to goitre. In the pituitary anterior lobe, on the other hand, the same characteristic changes take place in the basophilic cells as after thyroidectomy. The thyroid structure of hypophysectomised tadpoles corresponds to that of untreated hypophysectomised animals. Thiourea and thiouracil do not inhibit the thyroxine effect on thyroidectomised and hypophysectomised tadpoles. These findings indicate that the point of attack of thiouracil and thiourea lies in the follicular epithelium of the thyroid, and thus supportAstwood's hypothesis.     

Zur Frage des pH-Optimums des Pepsins

Summary Natural and purified proteins were split by crystallized pepsin. The break down of substrates was followed by a turbidimetric method. pH optima were found from 1.5 to 3.8. Only unpurified egg albumin had two optima, crystallin had one in the acid range. Ovomucoid not being split by pepsin, the second peak at pH 3.79 is referred to conalbumin. While the disintegration of caseinogen becomes slow with decreasing acidity, this is not true for casein (paracasein) which is well split up to pH 3.28 (cows casein) or 3,73 (womens casein). Nevertheless, the optimum is in the range of 1.5–2.0, like most proteins. Above this limit, the following optima were found: fibrinogen 2.93, thrombin 2.78, edestin 3.08, crystallized hemoglobin 3.19, conalbumin 3.79.     

Zur Biogenese des Lignins

Summary Potato germs grown in absence of light contain a substance which doubtless can be classified as lignin. This statement, though contradictory to the findings ofP. Klason, may be proved by microscopic staining methods as well as by chemical analysis. It is concluded that photo-energy is not necessary for the formation of lignin.     

Zur Kenntnis des Korkes

Ohne Zusammenfassung     

Zur Biosynthese des Ubichinons

Summary ¹⁴C labelled mevalonic acid is incorporated by the rat into the ubiquinone molecule. Vitamin E, however, is no precursor of ubiquinone. It is suggested that the ring component is essential for animals and that the isoprene side chain is at least partly built up by mevalonic acid.     

Zur Biosynthese des Plumierids

Summary It has been shown that the leaves ofPl. acutifolia incorporate acetate-1-¹⁴C and mevalonate-2-¹⁴C specifically for the formation of the aglycone moiety of plumieride.

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Wir danken dem Schweizerischen Nationalfonds sehr für die Unterstützung der Arbeit, Herrn Dr.J. Würsch (F. Hoffmann-La Roche & Cie., Basel) für markiertes Mevalonsäure-lakton und Herrn Prof.D. Arigoni (Zürich) für interessante Diskussionen.     

Zur Geschichte des Metermasses

Summary The history of the normal meter shows distinct steps of development. The meter itself was defined by French scientists as a national unit at the beginning of the great French Revolution and realized in 1799 by a platinum rod. A better reproduction of the unit of length was given in 1889 by a 90% Pt-10% Ir platinum bar of special cross section according to an international convention. Every substantial standard, however, has many disadvantages, besides the possibility of an entire loss by an accident. The red cadmium line was therefore used in 1893 to express the meter by the number of its wave lengths in air and a provisional resolution was adopted in 1927 on this basis. Much more suitable, however, is an orange line emitted at 63°K from the isotope⁸⁶Kr, which can be produced in a thermal diffusion column in the state of highest purity. Since 1960, the vacuum wave length of this element has served as the fundamental unit of length.     

Zur Wirkung des Calciums auf die Myofibrillen-ATPase des Herzmuskels

Summary The inhibition of cardiac myofibrillar ATPase activity by EDTA can be completely reversed by Ca⁺⁺ under certain experimental conditions. This shows that there is no fundamental difference between the reaction of cardiac myofibrillar ATPase and the tension development of glycerinated cardiac fibres, as was supposed byBriggs andHannah on account of the results ofParker andBerger.     

Zur Einteilung des Ostwaldschen Farbtonkreises

Summary The foundations of the division of the colour circle according toOstwald andRichter ² are subject to contradictions. A new division is calculated, based upon a limited formulation of the principle of inner symmetry. Finally different possibilities of connecting theOswald numbers and the trichromatic coordinates are discussed.

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Natuurkundig Laboratorium der N. V. Philips¹ Gloeilampenfabrieken Eindhoven, Nederland.     

Zur funktionellen Bedeutung der räumlichen Anordnung des Kristallkegels zum Rhabdom im Auge der Trachtbiene (Apis mellifica L.)

Summary The granular material found in the 4 sectors of the crystalline cone of varying electron density possibly causes a different absorption of incident polarized light. As the quadrants of the crystalline cone are rotated against the quadrants of the rhabdom, we can conclude that each rhabdomere may be stimulated by light of different physical qualities consequently providing a 4-to 8-fold pattern in the rhabdom of the ommatidia.

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Mit Unterstützung durch die Deutsche Forschungsgemeinschaft.     

Zur Konstitution des Resibufogenins und Artebufogenins

Summary The structure of Resibufogenin is unambiguously shown to be 3-hydroxy-14, 15-oxido-bufadien-(20, 22)-olide on the basis of new degradation work. Artebufogenin A and Artebufogenin B are 3-hydroxy-14-15-keto-bufadien-(20, 22)-olide and 3-Hydroxy-14-14-keto-bufadien-(20, 22)-olide, respectively.     

Zur Biosynthese des Verbenalins und Aucubins

Summary Verbena officinalis specifically incorporates 2-¹⁴C labelled mevalonic acid in the formation of the aglycone moiety of verbenalin (2). In aucubin (6), isolated fromVerbascum thapsus, the incorporation rate is very low and the main part of the activity is located in the sugar moiety.     

Zur Biosynthese des Cantharidins. I

Summary In contrast to the female, the adult males ofLytta vesicatoria (Coleopt. Meloidae) produced radioactive cantharidine on injection with¹⁴C-1-acetate and¹⁴C-2-mevalonate solutions. A partial degradation of the cantharidine showed that in the acetate experiment approximately of the activity occurred at C atoms 2 + 3 whereas with mevalonate approximately of the activity was at C atoms 8 + 9 and at C atoms 10 + 11. These results show that cantharidine is not formed by a tail to tail linkage of 2 isoprene units.

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Wir danken dem Schweizerischen Nationalfonds zur Förderung der wissenschaftlichen Forschung für die Unterstützung dieser Arbeit, Herrn Dr.J. Würsch (Physikalisch-chemische Abteilung der Firma F. Hoffmann-La Roche & Co. AG, Basel) für¹⁴C-2-Mevalolacton und unserer mikroanalytischen Abteilung (LeitungH. Frohofer) für die Aktivitätsbestimmungen.     

Zur Ausschaltung des Becquereleffektes in der Elektroretinographie

Summary Distortion of the electroretinogram by Becquerel effect may be excluded by using carbon rod instead of metallic wire in connecting the electrode.     

Zur Frage der thermoelastischen Eigenschaften des Nerven

Summary The thermo-elastic properties of nerve have been studied by measurements of the change in length caused by changes in temperature. The thermal coefficient (per °C) of linear expansion, always positive in sign, is of the order of 10^–4 for intact nerve and 10^–5 for dissected nerve.