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  • Articles  (12,567)
  • 1950-1954  (12,567)
  • 1953  (12,567)
  • Biology  (12,567)
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  • Articles  (12,567)
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  • 1950-1954  (12,567)
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  • 1
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    Electronic Resource
    Springer
    Development genes and evolution 146 (1953), S. 589-592 
    ISSN: 1432-041X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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  • 2
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    Development genes and evolution 146 (1953), S. 515-536 
    ISSN: 1432-041X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Zusammenfassung 1. Bei 2–3 Monate alten Larven vonTriton alpestris werden rechteckige Epidermisstücke aus der Flanke der einen Körperseite herausgeschnitten. 2. Die Wundfläche wird im Laufe von 24 Std durch allseitige Zuwanderung von Epidermiszellen bedeckt. 3. An der Wundheilung sind außer den Grundzellen der Epidermis auch die ausdifferenziertenLeydigschen Drüsenzellen in vollem Ausmaße beteiligt. 4. Über der Wundregion kommt es zu einer überschüssigen Akkumulation von Leydig-Zellen; ihr entspricht eine starke Verarmung in allen Epidermisarealen, welche die Wundränder umgeben. 5. Die durch Wanderung bedingte Veränderung in der Verteilungsdichte der Leydig-Zellen wurde quantitativ erfaßt, und der Einflußbereich der Wundregion bestimmt. 6. Zellvermehrung durch Mitose spielt bei den Regenerationsvorgängen bis zum 8. Tage nach der Operation keine nachweisbare Rolle. 7. Durch Colchicin und durch ein Aminoketon kann die reparative Zellbewegung gehemmt werden.
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  • 3
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    Development genes and evolution 146 (1953), S. 580-588 
    ISSN: 1432-041X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Zusammenfassung 1. Die sandalenförmige Einschnürung der Keimscheibe wird im allgemeinen bei Keimscheiben von wenig Urwirbelpaaren kenntlich; man kann jedoch die Stelle der späteren Einschnürung in frühere Entwicklungsstufen zurückverfolgen. 2. Die Area embryonalis zeigt zu der durch die Stelle der stärksten Verengung gelegten Querebene ein wechselndes Verhalten. Die Querebene trifft vorerst den Primitivstreifen, dann den Primitivknoten, hierauf das unsegmentierte kranial vom Knoten gelegene Mesoderm, endlich die Urwirbel. 3. Die tatsächliche Verschmälerung der Keimscheibe im Bereich der Einengung wird auf die medial gerichtete, zur Mesodermbildung führende Bewegung des Ektoblasten nachGraeper, zurückgeführt. 4. Die Verschiebung des Primitivknotens gegenüber der Einengungsstelle wird gleichfalls gestaltungsdynamisch erklärt, wobei wir zu ähnlichen Ergebnissen kamen wieGraeper undWetzel, wenngleich wir betreffs der genauen Richtung der Bewegungsphasen in einzelnen Punkten abweichen.
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  • 4
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    Development genes and evolution 146 (1953), S. 537-543 
    ISSN: 1432-041X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung 1. Es wurden an Hühnerkeimscheiben die Folgen einer zunehmend langen Abkühlung nach der Eiablage untersucht. 2. Bei einem Aufschub der Anbrütung bis zum 7. Tage zeigen die Keimlinge keine Änderungen der Morphogenese. In der Organisation von Keimlingen mit einem Aufschub von 12 und mehr Tagen entstehen Veränderungen der Entwicklung (Unterdrückung). Die länger zurückgehaltenen Embryonen neigen zu einer stärkeren Verkürzung ihrer Achse. 3. Die axialen Strukturen der Keimlinge werden in Gestalt und Ausdehnung reduziert, bis sie bei solchen, die vor der Bebrütung 15–20 Tage zurückgehalten waren, überhaupt fehlen. Die Keimscheiben dehnen sich zu einem flächigen Gebilde aus, das keine Anzeichen von Organisation mehr zeigt. 4. Hat die Abkühlung länger als 20 Tage gedauert, so werden die Keimlinge zunehmend entwicklungsunfähig. 5. Die wahrscheinliche Erklärung für die Entstehung dieser morphogenetischen Merkmale wird in der Denaturierung von „Zellsubstanzen“ durch Wasserverlust, in der Unterdrückung von mitotischer Aktivität und von morphogenetischen Bewegungen der Zellen des Keimlings gesucht.
    Notes: Summary 1. The progressive effects of temperature fasting on the blastoderms of chick have been studied. 2. The blastoderms do not show any morphogenetic change up to the 7th day of delay prior to incubation. Embryological changes in form of suppression arise in the organisation of blastoderms delayed over 12 days or more. The axes of the embryos tend to be more shortened in the further delayed embryos. 3. The axial structures of the blastoderms suffer reduction in shape and size until they disappear in the blastoderms kept waiting for 15 to 20 days. The blastoderms enlarge into a sheet-like structure without any mark of organisation. 4. The blastoderms become gradually incapacitated beyond the temperature-fasting for over 20 days. 5. The probable mechanism of these morphogenetic features have been sought in the denaturation of “Cell substances” by dehydration, suppression of mitotic activities and morphogenetic movements of cells of the blastoderms.
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  • 5
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    Cellular and molecular life sciences 9 (1953), S. 369-369 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Zusammenfassung Die infraroten und ultravioletten Spektren und analytische Daten von Geissospermin wurden diskutiert. Die Spaltung von Geissospermin mit konzentrierter Salzsäure wurde wiederholt, und ein Spaltprodukt C19H26ON2 wurde durch Gegenstromverteilung rein iscliert und durch ein kristallines Pikrolonat charakterisiert. Dieses Produkt besitzt ein Dihydroindolspektrum und trägt die N-methylgruppe des Geissospermins.
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  • 6
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    Cellular and molecular life sciences 9 (1953), S. 373-374 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Zusammenfassung Durch Gefriertrocknung nachAltmann-Gersh wurden zytologische Präparate von einer genetisch geprüften polyploiden Serie von Hefe hergestellt. Die gemessenen Werte für Kern- und Zellgrössen stimmen in der theoretisch erwarteten Weise mit dem Grade der Polyploidie überein. Damit ist eine von höheren Organismen bekannte zytologische Erscheinung zum erstenmal für Mikroorganismen demonstriert. Die Befunde stehen im Widerspruch zuLindegrens Annahme einer «Kernvakuole» und zuSubramaniams genetisch nicht fundierten Einwänden gegen die Brauchbarkeit von Einzelsporen-Kulturen, ebenso zur Ansicht des letztgenannten Autors, dass zytologische Unterschiede bestehen zwischen Zellen aus Gärungs- und solchen aus aeroben Kulturen.
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  • 7
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    Cellular and molecular life sciences 9 (1953), S. 377-379 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary An autoradiographic method, based on the observation of individual particles, was used to determine the relative specific radioactivity of RNA and of the proteins in the different parts of the oocytes ofAsterias rubens. The nucleolus incorporates glycine in both fractions about 100 times more rapidly than the cytoplasm.
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  • 8
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    Cellular and molecular life sciences 9 (1953), S. 22-23 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Survival curves ofEscherichia coli irradiated with X-rays of 180 KeV and 31 MeV are identical within the experimental error. Probit analysis of the data was performed.
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  • 9
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    Cellular and molecular life sciences 9 (1953), S. 466-468 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Zusammenfassung Borrelina-Virose wird in Larven vonBombyx mori nach Fütterung von 0,01% Natriumfluorid manifest. Das massenhafte Auftreten der Viren erfolgt trotz Ausschluss äusserer Infektion. Es wird eine Aktivierung von Elementen angenommen, die eine latente und spezielle Viruspotenz besitzen. Auf die enzymhemmende Wirkung des Natriumfluorids beim Gluzidabbau wird hingewiesen.
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  • 10
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    Cellular and molecular life sciences 9 (1953), S. 472-473 
    ISSN: 1420-9071
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  • 11
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    Cellular and molecular life sciences 9 (1953), S. 41-61 
    ISSN: 1420-9071
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  • 12
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    Cellular and molecular life sciences 9 (1953), S. 107-110 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Reserpin, a new, highly active alcaloid fromRauwolfia serpentina benth., shows a very marked hypnotic effect and lowers the blood pressure. Reserpin inhibits pressor responses evoked by electrical stimulation of the afferent vagus and sciatic nerves, and inhibits the pressor reflex of the carotid sinus. It does not inhibit pressor responses evoked by electrical stimulation of the splanchnic nerves. Reserpin has no peripheral sympathicolytic and no ganglionic blocking activity; the action of sympathicomimetic substances, e.g. adrenaline, nor-adrenaline, ephedrine, is enhanced. It does not potentiate the acetylcholine effect. The blood pressure effect is not inhibited by atropine and by cutting the vagi and depressor nerves. Reserpin stimulates peristalsis. The neuro-muscular transmission is not impaired. There is evidence, that central portions of the sympathetic system are inhibited byReserpin.
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  • 13
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    Cellular and molecular life sciences 9 (1953), S. 16-17 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Zusammenfassung Chromatographische Beobachtungen stützen die auf spektraltheoretische Berechnungen basierte Annahme vonH. Kuhn, dass in gewissen Zyaninfarbstofflösungen ein Gemisch von cis-trans-isomeren Formen vorliegt.
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  • 14
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    Cellular and molecular life sciences 9 (1953), S. 7-16 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A concise survey is given of the possibilities of producingmotherlike descendants: the so-called “maternal hybrids”, after interspecific pollinations in flowering plants. On the basis of his extensive experiments in pollination and interspecific crossings with species of different sections of the genusPrimula, the author believes that he has proved that the motherlike descendants from interspecific crossings inPrimula—as in other genera likeSolanum andDigitalis—are the result neither of amphimictic combination nor of partial aposporic or pseudogamic reproduction. They are rather the result of parthenogenetic embryo formation in developing seeds, the smaller part perhaps of haplo-, the greater and more conspicuous part of diplo-parthenogenesis. With these unexpected additions, the possibilities of the origin of motherlike descendants from interspecific crossings now include: (1) Mother (or Father-) like descendants fromnormal amphimictic reproduction after crossings of two species from which the one transfers the dominant, the other the recessive alternatives of the distinguishing morphological and physiological characters. (2) Motherlike descendants ofnon-amphimictic origin after interspecific pollination on and withobligate or partial aposporic and pseudogamic species. (3) Motherlike descendants ofnon-amphimictic origin from interspecific crossings of normal sexual species,from seeds with embryos from haplo- or diplo-parthenogenetic development. With the description of this third category of formation of motherlike descendants, the circle of possibilities seems to be closed. One may now presume that all facts or “maternal hybrids” cited—except those from crossings with definitely proved “experimental errors”—can be explained by one of the possibilities cited above.
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  • 15
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    Cellular and molecular life sciences 9 (1953), S. 23-24 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Zusammenfassung Von 12 streptomyzinfestenB. tularense-Stämmen wurden 11 in einer 1/160 normalen NaCl-Lösung agglutiniert und waren von niedrigerer Virulenz als die durch dieselbe NaCl-Lösung nicht agglutinable, hochvirulente Ausgangskultur. Einer dieser streptomyzinfesten, nicht virulenten Stämme war fähig, weisse Mäuse gegen eine Million 50%iger tödlicher Dosen des Ausgangsstammes zu immunisieren.
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  • 16
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    Cellular and molecular life sciences 9 (1953), S. 26-27 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Zusammenfassung Die Wirkungsgeschwindigkeiten von intravenös injiziertem Vitamin K1, Methylnaphthochinon und Synkavit in Vitamin-K-frei ernährten Küken wurden verglichen. Es zeigte sich, dass in den ersten Stunden nach der Injektion Vitamin K1 die Prothrombinzeit viel schneller zum Absinken brachte als die beiden anderen Verbindungen.
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  • 17
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    Cellular and molecular life sciences 9 (1953), S. 29-30 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In castrated guinea pigs injected with testosterone propionate (100–250 γ per 100 g daily for 4 days), the thymus underwent atrophic modifications, characterized chiefly by the diminution of the lymphocytes. In thyroidectomized castrates, injected with thyroxine (6 γ per 100 g and 24 h) in order to prevent the thyroprive atrophy of the thymus, testosterone injections failed to produce any modifications of the thymus. Thus structural changes induced by testosterone injections could be interpreted as the consequence of the stimulation of the thyroid by this hormone.
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  • 18
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    Cellular and molecular life sciences 9 (1953), S. 151-152 
    ISSN: 1420-9071
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    Topics: Biology , Medicine
    Notes: Zusammenfassung Bei horizontaler Papierchromatographie auf Rundfiltern wird das Trennungsvermögen grösser, wenn man die mobile Phase an einem Punkt in Peripherienähe zuführt und die zu chromatographierenden Substanzen auf einen um diesen Punkt gelegenen Kreisbogen aufträgt.
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  • 19
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    Cellular and molecular life sciences 9 (1953), S. 156-159 
    ISSN: 1420-9071
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    Cellular and molecular life sciences 9 (1953), S. 384-385 
    ISSN: 1420-9071
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    Notes: Summary The application of monosemicarbazon derivate of Adrenochrom (Adrenoxyl) indicates a muscle-active effect (decrease of contraction and retardation of muscle tiredness) in rats, in rabbits and in man.
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  • 21
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    Cellular and molecular life sciences 9 (1953), S. 387-388 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary W. v. Buddenbrock and his collaborators claim to have demonstrated optomotor reactions due to the apparent displacement of the visual field caused by the animal's normal active movement. In two of the three cases mentioned (Carcinus, Calandra) the evidence brought forward is insufficient and needs further experimental investigation. In the third case (Aeschna) their conclusion is obviously erroneous: the sensory stimuli eliciting optomotor reactions are caused by the passive displacement (turning) inflicted upon the animal artificially and not by its active movement as such.
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  • 22
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    Cellular and molecular life sciences 9 (1953), S. 391-394 
    ISSN: 1420-9071
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    Notes: Summary A mathematical theory is developed for an apparatus seperating chemical mixtures, which has been studied byR. Signer and assistants in Berne. The method employed is one of extraction by the principle of counter-current in a series of coupled cells. The concentrations of the resulting fractions are given as functions of time, when the concentration of the solutions entering the middle cell of the apparatus is a known function of time.
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  • 23
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    Cellular and molecular life sciences 9 (1953), S. 395-396 
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  • 24
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    Cellular and molecular life sciences 9 (1953), S. 178-179 
    ISSN: 1420-9071
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    Notes: Résumé Exposé d'une nouvelle hypothèse sur l'origine biochimique de la colchicine dans la plante. Il est supposé que l'acide trihydroxyphénylpyruvique agit commeprécurseur de cet alcaloïde en subissant les transformations décrites par les formules (I) à (VI). On constate une analogie entre ce mécanisme biogénétique et l'origine chimique de la purpurogalline de même qu'une ressemblance structurale entre la morphine et la colchicine. Le classement de la colchicine au nombre des alcaloïdes de la famille des phényléthylamines serait ainsi justifié.
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    Cellular and molecular life sciences 9 (1953), S. 181-181 
    ISSN: 1420-9071
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    Notes: Summary There is a difference of the diameter of elementary fibrils in cellulose measured with the electron microscope or determined by X-ray analysis. This is explained by the assumption that the elementary fibrils have a well crystallized interior covered by a paracrystalline peripheral layer.
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    Cellular and molecular life sciences 9 (1953), S. 187-189 
    ISSN: 1420-9071
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    Notes: Summary It has been observed thatRinger solutions without potassium have the capacity of annulling the contracture induced by ouabain and of restoring the contractility of an isolated frog's heart. If after washing with theRinger solution without potassium, the heart is perfused with normalRinger solution, the organ once again passes into contracture. Taking into considerationFleckenstein's theory of muscle contraction the phenomenon is interpreted by supposing thatRinger solution deprived of potassium has the capacity of restoring the cationic gradient which has been disturbed by the state of contracture.
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    Cellular and molecular life sciences 9 (1953), S. 425-426 
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    Notes: Summary Based on former experiments it is shown that the venous pulse on the isolated vein of the membrane ofChiroptera (preparation of the venous sack) is caused by a humoral factor, which is isolated in the serum dialysate of bats and other mammals asl-arginine. This aminoacid is responsible for the increasing of amplitude, tonus, and frequency.
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    Cellular and molecular life sciences 9 (1953), S. 427-428 
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    Notes: Summary The most interesting antagonists of decamethonium iodide known up to now are pentamethonium iodide and tubocurarine. In fact several other compounds principally Paludrine, bis-(2 heptyl)amine and a substituted butylamine are effective inhibitors of the depolarising quaternary ammonium salt in the cat. Stilbamidine, Pentamidine, compound 48–80 and Tween 20 have the same property but are less active. All these compounds have the common property to be histamine liberators.
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    Cellular and molecular life sciences 9 (1953), S. 397-405 
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    Cellular and molecular life sciences 9 (1953), S. 405-412 
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    Notes: Summary Synaptotropic substances, i.e. substances acting on autonomic ganglia, may also have an action on the suprarenal medulla which is an efferent organ of the sympathetic nervous system and can be regarded as a modified sympathetic ganglion. Moreover, synaptotropic substances exert effects on certain afferent structures bearing a close anatomical and functional relationship to the autonomic nervous system, e.g. the chemoreceptor system in the carotid body and the cardiac receptors responsible for theBezold-Jarisch effect. As a rule, synaptotropic excitatory substances stimulate the suprarenal medulla (secretion of hormone) and the other afferent structures referred to, while synaptotropic inhibitory substances exert a depressive action. There are, however, exceptions to this rule. It seems especially remarkable that synaptotropic substances are also able to exert effects on afferent structures in which there are no synapses. The presence of a morphologically distinct synapse is not, therefore, a necessary condition for their action.
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    Cellular and molecular life sciences 9 (1953), S. 422-424 
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    Notes: Résumé L'auteur a fait une étude microspectrophotométrique des cellules dePurkinje du rat blanc adulte. La courbe de distribution des fréquences montre une remarquable dispersion des valeurs d'extinction cytoplasmiques à 2650 Å et 2800 Å, avec un groupement des fréquences plus hautes vers les valeurs basses. L'étude des spectres d'absorption a démontré un maximum d'absorption des nucléotides et un maximum protéique, même dans le cytoplasme des cellules moins absorbantes. La digestion des coupes par une ribonucléase dépourvue d'activité protéolytique a provoqué une diminution considérable des valeurs d'extinction cytoplasmique à 2650 Å et 2800 Å; aux mêmes longueurs d'onde l'extraction par l'eau distillée a déterminé une réduction d'extinction très variable, mais en tout cas bien inférieure à celle provoquée par l'enzyme. Après la digestion par la ribonucléase, ainsi qu'après l'extraction par l'eau, on a observé une augmentation plus ou moins remarquable des pertes non spécifiques de lumière dues à la diffraction et à la réflexion dans la préparation.
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    Cellular and molecular life sciences 9 (1953), S. 425-425 
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    Notes: Zusammenfassung Der Eiweissanteil in Gegenwart von radioaktivemdl-Alanin gezüchteter Hefe zeigt eine Aktivitatsverminderung, wenn der Suspension nicht radioaktivesd- oderl-Alanin zugefügt wird. Offenbar vermag die Hefezelle beide Isomere auszunützen.
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    Cellular and molecular life sciences 9 (1953), S. 428-429 
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    Notes: Summary The circulatory efficiency of the snail's heart depends upon the cooperation of the heart s. str. and the pericardium. The circulation rate has been determined; it depends upon the pressure in the lung vein and in the aorta. Heart activity becomes most efficient (“optimal”) if the input pressure is about 11, the output pressure about 19 cm H2O (table). Increasing circulatory demand decreases the frequency of the heart.
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    Cellular and molecular life sciences 9 (1953), S. 436-436 
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    Cellular and molecular life sciences 9 (1953), S. 457-459 
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    Notes: Zusammenfassung Es wird ein biogenetischer Weg vorgeschlagen, der zu Lysergsäure, dem gemeinsamen Teilstück aller Mutterkornalkaloide, führt. Der grundlegende Schritt der Biogenese besteht nach unserem Vorschlag in der Kondensation von Dihydro-Nikotinsäure (oder einem Derivat derselben) mit dem Chinon III, das aus 5-Oxytryptophan (oder einer gleichwertigen Verbindung) sich bilden sollte.
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    Cellular and molecular life sciences 9 (1953), S. 459-460 
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    Notes: Summary Aspartic acid changes on being heated without solvents to a not completely uniform substance of anhydride character. This appears to have a structure II different from that assigned to it by earlier investigators. Mild hydrolysis produces a mixture of polyaspartic acids which has been freed by dialysis from constituents of low molecular weight leaving a polypeptide with the approximate molecular weight of 8,200. It is presumed that this polyaspartic acid, differing from the known synthetic α-polyaspartic acid, closely approximates to the β-polyaspartic acid of structure IV.
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    Cellular and molecular life sciences 9 (1953), S. 70-71 
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    Notes: Summary According to our paper chromatographic tests, human, cow's, and rat's milk all contain small quantities of glucose, galactose and glutamic acid, as well as a sugar-like, nitrogen-containing substance of which the hydrolysis products were studied. In human milk only, we found a non-identified aldohexose.
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    Notes: Zusammenfassung Während grosse Dosen von Pregnenolon die Ausbildung abdomineller Fibroide unter der Einwirkung von Östrogenen zu verhindern vermögen (antifibromatogener Effekt), war mitΔ 16-Dehydropregnenolon kein solcher Effekt zu erzielen. Die mangelnde Wirksamkeit der letzteren Verbindung lässt sich vielleicht mit ihrer Umwandlung durch die Nebennierein das bekannterweise unwirksameΔ 16-Dehydroprogesteron erklären, vielleicht mit der Annahme einer Unvereinbarkeit derΔ 16-Doppelbindung mit antifibromatogener Wirkung.
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    Cellular and molecular life sciences 9 (1953), S. 75-80 
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    Notes: Zusammenfassung Die mit Tetradenanalyse durchgeführten Untersuchungen fordern eine grundsätzliche Modifikation der Mendel-Theorie. Die Experimente führen zur Annahme, dass das Gen eine grosse Zahl übertragbarer Bestandteile trägt, die ringförmig um das Chromosom gelagert sind. Diese Teilchen können bei der Reduktion ungleichmässig auf die Allele verteilt werden. Gewisse Gene werden als « Enzym-Matrizen-Gene » (enzyme-template) bezeichnet, und ihre übertragbaren Bestandteile werden als Spiegelbilder des Substrats aufgefasst. Die Untersuchung einer multiplen Allelserie eines Enzyme-template-Gens ergab, dass das Gen nicht selbst das Enzym darstellt, sondern nur als eine Rezeptorstelle wirkt, die durch die Einwirkung des Substrats angeregt wird. Dies führt zur Bildung des Enzyms.
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    Cellular and molecular life sciences 9 (1953), S. 94-95 
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    Notes: Zusammenfassung Es wird der Versuch gemacht, den Einfluss des Lichtes auf die Samenkeimung (zum Beispiel Salatsamen, var. Grand Rapids) auf einen physikochemischen Mechanismus zurückzuführen. Dieser besteht darin, dass Elektronen in metastabilen Zuständen in Elektronenfallen festgehalten werden. Diese Auffassung wird dadurch gestützt, dass der Einfluss von Licht verschiedener Wellenlängen, verschiedener Temperaturen und verschiedener Sauerstoffkonzentrationen auf die Samenkeimung und auf bestimmte physiko-chemische Prozesse, die auf dem oben erwähnten Elektronenmechanismus beruhen, ähnlich ist.
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    Cellular and molecular life sciences 9 (1953), S. 81-88 
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    Cellular and molecular life sciences 9 (1953), S. 88-89 
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    Notes: Zusammenfassung In kurzer Form wird der Inhalt gewisser (orthoschematischer) sphärischer Polyeder für eine willkürliche Dimensionenzahl mitgeteilt. Diese Formel bildet die Lösung eines vonSchläfli aufgestellten Systems linearer partieller Differentialgleichungen erster Ordnung.
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    Cellular and molecular life sciences 9 (1953), S. 91-93 
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    Notes: Zusammenfassung Aus der Veresterungsgeschwindigkeit der stereoisomeren Menthole mitp-Nitrobenzoylchlorid lässt sich schliessen, dass diese Moleküle in derjenigen Konstellation reagieren, in welcher die Oxygruppe eine äquatoriale Stellung einnimmt. In starren Molekülen (wie dietrans-Dekalole), bei denen die Verschiebung einer Oxyoder Estergruppe von der polaren in die äquatoriale Stellung nicht möglich ist, findet man besonders grosse Unterschiede in der Verseifungsgeschwindigkeit von epimeren Estern. Der Unterschied in der Verseifungsgeschwindigkeit von Estern der epimerencis-α-Dekalole, die beide die Oxygruppe in der äquatorialen Stellung haben, lässt sich durch verschiedene sterische Hinderung durch eins der Wasserstoffatome in derperi-Stellung erklären.
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    Cellular and molecular life sciences 9 (1953), S. 110-111 
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    Notes: Summary Our experiments suggest that a M-shaped curve of frequency distribution does not need to be always the result of non-homogeneous materiali.
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    Cellular and molecular life sciences 9 (1953), S. 112-114 
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    Notes: Summary Flying and swimming animals need to be able to avoid passive displacement by air and water currents. Optomotor reactions essentially serve this purpose. The animals must be able to distinguish precisely between sensory stimulation caused by passive displacement and by active locomotion. Stimulation due to active movements does not release optomotor reactions. Apparent exceptions to this rule, occurring only under artificial circumstances, are caused by a derangement of either normal sensory stimulation or normal movement and, consequently, of their normal correlation. Examples of both cases are discussed.
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    Cellular and molecular life sciences 9 (1953), S. 120-120 
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    Cellular and molecular life sciences 9 (1953), S. 138-140 
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    Notes: Summary Comparative analysis of functional antlers and bones of the legs in young fallow-deer shows in general the same chemical structure. The amount of N, P, and Ca in the velvet was determined. To confirm the growth in the points of the antlers 2 young stags with growing and functional antlers respectively got injections of radioactive P. The radiograms of the growing antlers cut in thin slices show very clearly an intensive activity at the pointed ends whereas in the functional antler only little activity is seen below the base. The Ca of the blood remains relatively constant.
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    Cellular and molecular life sciences 9 (1953), S. 111-112 
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    Notes: Zusammenfassung Eswurde in elektrophysiologischen Versuchen gezeigt, dass bei dem Affen (Macaca mulatta) die spinalen Motoneuronen von den kortikospinalen Neuronen monosynaptisch aktiviert werden können. Einige Eigenschaften der monosynaptischen Aktivität wurden beschrieben und einige klinische Aspekte aufgezeigt.
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    Cellular and molecular life sciences 9 (1953), S. 263-264 
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    Notes: Summary A traumatic shock decreases the ribonucleic acid content of the liver in the rat, as shown by both cytochemical and quantitative methods. In homogenates of the livers from the operated animals, the ribonucleic acid content increases in the supernatant after ultracentrifugation while it decreases in the mitochondrial fraction. The desoxyribonucleic acid is not affected by the traumatic shock.
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    Cellular and molecular life sciences 9 (1953), S. 266-267 
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    Notes: Zusammenfassung Es wird gezeigt, dass Serum aus adrenalinvorbehandelten Ratten, vier Stunden nach Adrenalininjektion in normale Tiere transfundiert, bereits nach 30 min eine mehr als 50%ige Eosinopenie verursacht. Das Auftreten eines humoralen Wirkstoffes während der Eosinopenie wird diskutiert und mit Cortison verglichen.
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    Cellular and molecular life sciences 9 (1953), S. 268-268 
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    Notes: Summary Male and female albino rats were treated with Myleran (CH3SO2OCH2CH2CH2CH2OSO2CH3). Particular attention was paid to the histological examinations of the gonads of these animals. The testes as well as the ovaries were badly damaged. The male germinal epithelium was completely destroyed. Oocytes and follicles were no longer present in the ovaries.
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    Cellular and molecular life sciences 9 (1953), S. 272-273 
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    Cellular and molecular life sciences 9 (1953), S. 286-287 
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    Notes: Summary The author maintains that a great part of the observed yearly variation in the rate of Quarz-clocks is caused by the «Lorentz-contraction» of the earth and that in this case the yearly curves of the clock-corrections at southern stations must agree with the reflexes of those on northern stations. The fact of this phenomenon is demonstrated by some figures, and the existence of the «Lorentz-contraction» is thus proved.
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    Cellular and molecular life sciences 9 (1953), S. 288-289 
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    Notes: Summary Exchange experiments at room temperature with differently labelled CoII [CoIICoIII(CN)6]2 (the difference in labelling depends upon which Co is made radio-active) indicate that Co is bound in three different ways. The amount of exchange of CoIII in the complex was negligible. The CoII statistically occupying the holes in the main cubic lattice (Zwischengitter) exchanges quickly and completely, while the remaining CoII participates slowly in exchange reactions. Due to theSzilard-Chalmers effect,60Co accumulated in the holes of the main cubic lattice of CuII[CuIICoIII(CN)6]2 which had been exposed to neutron bombardment. This60Co was removed from the interior of the solid compound by exchange with Cu2+ and electrolytically separated. The enrichment was greater than 106, and approximately 60% of the60Co could be extracted.
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    Cellular and molecular life sciences 9 (1953), S. 152-153 
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    Notes: Zusammenfassung Ein neuer, ausSambucus-nigra-Beeren extrahierter Farbstoff wird in die Histologie eingeführt undSambuzianin benannt. Sambuzianin zeigt die Kennzeichen eines guten Kernfarbstoffs sowie eines empfindlichen Indikators. Die Farblösung ergibt einen pH-abhängigen Farbumschlag von Rot zu Blau. Die mit Sambuzianin gefärbten mikroskopischen Präparate weisen Unterschiede im Farbton auf, was für einen histochemischen Indikator eines zellulären pH-Unterschiedes zu sprechen scheint.
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    Cellular and molecular life sciences 9 (1953), S. 175-176 
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    Notes: Summary Oriented overgrowths of crystals of organic compounds on cleavage layers of talc and cadmium iodide and of NH4J on talc are described. These oriented overgrowths are remarkable in view of the fact that thevan der Waals forces between the layers of these substrate crystal lattices are only weak. The crystals of NH4J oriented on talc have a square contour in contrast to the triangular crystals of NH4J oriented on mica.
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    Cellular and molecular life sciences 9 (1953), S. 176-177 
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    Notes: Résumé La phosphorylase de pommes de terre a été purifiée par deux fractionnements au sulfate d'ammonium, deux fractionnements au sulfate d'ammonium en présence de NaCl et une chromatographie sur colonne d'amidon. On a obtenu ainsi un enrichissement de 300 fois par rapport à l'extrait brut. Le produit purifié ne montre qu'une seule composante à l'électrophorèse; il est dépourvu de maltase et de phosphatase, par contre il est souvent contaminé par des traces d'α-amylase. L'inhibition de l'enzyme par le glucose est du type compétitif. La phosphorylase de pommes de terre se distingue de la phosphorylase de muscle principalement par le fait qu'à l'état pur, elle n'est pas inhibée par la phloridzine et qu'elle possède une affinité pratiquement nulle vis-à-vis du glycogène.
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    Cellular and molecular life sciences 9 (1953), S. 310-310 
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    Notes: Zusammenfassung Es wird eine Methode zur elektronenoptischen Prüfung der peritonealen Mastzellen der Ratte beschrieben. Bestimmte elektronenmikroskopische Beobachtungen an diesen Zellstrukturen werden aufgezeigt.
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    Notes: Summary A new crystalline compound has been isolated from beef adrenal extracts. In three different assay methods using epinephrectomised rats or dogs it was found to be from 30 to 100 times as potent as cortexone (11-deoxy-corticosterone) or its acetate.
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    Cellular and molecular life sciences 9 (1953), S. 331-333 
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    Notes: Zusammenfassung Durch alkalische Hydrolyse wird Reserpin in Reserpinsäure, 3,4,5-Trimethoxybenzoesäure und Methanol gespalten. Das Esteralkaloid liess sich aus diesen Spaltstücken wieder resynthetisieren.
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    Cellular and molecular life sciences 9 (1953), S. 186-187 
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    Notes: Zusammenfassung Der Verlauf der akuten letalen Sublimatvergiftung bei der Ratte kann durch wiederholte subkutane Enteramininjektionen insofern beeinflusst werden, dass der Tod bei der Mehrzahl der Tiere verzögert wird und dass etwa 20% der Tiere die Vergiftung überleben. Die protektive Wirkung des Enteramins kommt dadurch zustande, dass die Substanz eine partielle pharmakologische Ausschaltung der Niere aus dem allgemeinen Kreislauf verursacht (Drosselung des afferenten Gefässsystems des Glomerulus) und damit eine verminderte Zufuhr des nephrotoxischen Stoffes zur Niere.
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    Cellular and molecular life sciences 9 (1953), S. 189-191 
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    Notes: Summary A brief description is given of growth experiments with rats, the animals receiving 10–15% cod liver oil in their diets. Use was made of normal and rancid oils, either unheated or heated at 230°C in vacuo for 3 h. The effects of large doses of α-tocopherol acetate, given per os, were also studied.
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    Cellular and molecular life sciences 9 (1953), S. 195-196 
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    Cellular and molecular life sciences 9 (1953), S. 261-262 
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    Notes: Resumé Les auteurs ont étudié l'action de l'hypoxie sur la prolifération des mégaloblastes dans l'anémie pernicieuse et ont mis en évidence un effet inhibiteur. Le phénomène est analogue à celui qui a été démontré pour l'érythroblaste de la moelle osseuse normale, mais il en diffère en ce sens que la sensibilité négative du mégaloblaste est plus grande que celle du normoblaste. Il n'est pas encore établi s'il s'agit d'une action spécifique en rapport avec la biologie différente des deux cellules ou simplement liée à leur différent degré d'activité prolifératrice, plus élevé pour le mégaloblaste que pour le normoblaste.
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    Cellular and molecular life sciences 9 (1953), S. 201-206 
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    Notes: Summary In this paper, written for non-astronomers, are summarized some of the results of a series of spectro-photometric investigations of the continuous spectrum of early-type stars (hot stars) carried on at the Institut d'Astrophysique de Paris; most of the observations were collected at the Jungfraujoch Scientific Station. The determination of the stellar temperatures is one of the main subjects of this work. The measurement of the surface temperature of a star would be very easy if the star were radiating like a black body. But this assumption is far from being fulfilled and the observation of the continuous spectrum of a star gives, instead of the true surface temperature, the “colour temperature” of the stellar radiation, a parameter which is not a temperature but characterizes the distribution of energy in the spectrum. From this and several other data, the temperature may finally be obtained by theoretical means. A new method is described which allows a direct evaluation of the temperature of the external layer of a star by the observation of the radiation emitted in the centre of the first, strongly absorbedBalmer lines. Moreover this method gives the brightness temperatures and then the apparent diameter of the star. The radii of two white dwarfs have been determined by this method. Among the other results, two are briefly given: a method for the classification of early-type stars depending on the measurement of the magnitude of the discontinuity occuring near the limit of theBalmer series and of its position (D. Chalonge, L. Divan), and a new investigation of the continuous absorption by interstellar dust (L. Divan) showing a remarkable constancy in its absorbing properties in various directions of the galaxy.
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    Cellular and molecular life sciences 9 (1953), S. 276-276 
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    Cellular and molecular life sciences 9 (1953), S. 289-291 
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    Notes: Summary When slowly dried up in their culture medium, bacteria show chondrioids (equivalents of mitochondria) which are entirely different from the nucleoïds (equivalents of nuclei). Observations are made in the electron microscope by means of the replica technique, or directly with the phase contrast microscope. The chondrioids contain the Formazan deposited by vital reduction of Tetrazol.
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    Cellular and molecular life sciences 9 (1953), S. 293-293 
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    Notes: Zusammenfassung Im Schleim verschiedener Herkunft sind ausserordentlich dünne Membranbildungen mit der lichtmikroskopischen Kontrastmethode des Autors zu beobachten.
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    Cellular and molecular life sciences 9 (1953), S. 294-295 
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    Notes: Summary De-nucleated eggs ofSphaerechinus granularis were fertilised with sperms ofPsammechinus microtuberculatus andParacentrotus lividus (heterosperm merogones). It was possible to culture 15 embryos up to the pluteus stage. The skeletons, the relative lengths of the first pair of lobes, the body form of the young merogones and the ciliated bands of the older merogones all show paternal characters. In the older merogones, the vertex was rounded and the lobes more lobulate than is characteristic forSphaerechinus.
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    Notes: Zusammenfassung Die Degradationsprodukte, die sich bei der Hydrolyse der Purine, der Pyrimidine und der Nukleinsäuren bilden, werden mittels runder Filterpapierscheiben chromatographisch untersucht. Adenine, Nukleinsäuren und Adeninverbindungen zeigen bei einer Säurehydrolyse ausser einem Band, das den Platz des Glycin einnimmt, noch ein weiteres Band. Dieses Band ist versuchsweise als 4(5)-amino-5(4)-imidazol Carboxamidin charakterisiert worden. Die Bedeutung dieser Ergebnisse für die quantitative Analyse der Nukleinsäuren und Adeninverbindungen wird in der vorliegenden Arbeit erörtert.
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    Cellular and molecular life sciences 9 (1953), S. 227-229 
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    Cellular and molecular life sciences 9 (1953), S. 236-236 
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    Cellular and molecular life sciences 9 (1953), S. 234-236 
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    Notes: Summary The earliest hominid predecessors as yet known, the Australopithecines, show that the branch leading to man was separated from the group of the anthropoids as early as the Tertiary. The Australopithecines as a group show great variability. The group contains in its genetic make-up all the characteristics of the representatives of the later stages. The presence of the primitive forms of many human characteristics has led us to include in the human line of evolution only those types which have remained primitively human (Australopithecus, Steinheim, Swanscombe, Fontéchevade, Piltdown).Pithecanthropus and Neanderthals are not to be considered as stages of a higher evolution but as sidebranches of thesapiens type.
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    Cellular and molecular life sciences 9 (1953), S. 242-252 
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    Notes: Summary Recent advances in the development of procedures for the fractionation of human blood have been reviewed, with a short introduction stressing the underlying theoretical basis of such procedures. Due consideration has been given to the isolation of the formed elements, obtained for the first time in a state resembling that of nature. Furthermore, some detailed investigations upon plasma proteins obtained by the older and by newer methods have been reviewed.
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    Cellular and molecular life sciences 9 (1953), S. 254-256 
    ISSN: 1420-9071
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    Notes: Zusammenfassung Das IR.-Absorptionsspektrum des Alkaloids Ajmalin zeigt die typische (7,24 µ) in der Seitenkette (festgestllt mitKuhn-Roth); bei 5,92 µ erscheint die Bande der Karbonylgruppe. Ajmalin wurde durch Abbau mit Selen in Ind-N-methyl-harman übergeführt. Durch Kalischmelze lässt sich Ajmalin in eine kristalline Base (in kleiner Menge), eine stickstoffreie Säure und Indol-2-Karbonsäure aufspalten. Auf Grund dieser Spaltstücke wurde eine mögliche Strukturformel für Ajmalin diskutiert.
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    Notes: Zusammenfassung Eine Prüfung der Bedingungen zur Erzielung einer antibakteriellen Wirkung in der Tbc-Therapie hat uns dazu geführt, ein Molekülschema zu verwirklichen. Für eine gleiche Anzahl polarer Hydroxylreste enthaltender Gruppen, die durch ätherische Sauerstoffbrücken an den hydrophoben Teil des Moleküls gebunden sind, tritt in diesem Modell eine tuberkulostatische Wirkung auf, wenn das Molekül ausserdem eine basische Gruppe enthält. Die Wirkung wird noch verstärkt durch einen aliphatischen Rest in einer zur basischen Gruppe benachbarten Stellung.
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    Cellular and molecular life sciences 9 (1953), S. 326-328 
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    Notes: Résumé L'auteur propose des méthodes simples pour lutter contre les pertes énormes dues aux leucoses qui sévissent dans les élevages commerciaux de nombreux pays. Ces leucoses comprennent des leucémies, des sarcomes, des neurolymphomatoses et des ostéopétroses. Elles sont provoquées par un groupe de virus étroitement apparentés. L'auteur étudie deux modes de propagation: Le premier, intéressant surtout les poussins, s'effectuerait par l'intermédiaire d'arthropodes parasites. De bonnes conditions d'élevage et l'utilisation des insecticides modernes permettrait d'y remédier. Le deuxième s'effectue par transmission du virus des poules infectées à leur descendance par l'intermédiaire de l'œuf. Comme le pouvoir infectueux du virus diminue avec l'âge de l'hôte, cette transmission se produit surtout lorsqu'on utilise pour les faire couver des œufs du premier cycle annuel de ponte et est très réduite si les œufs utilisés dans ce but proviennent de cycles plus tardifs. Etant donné qu'entre les virus l'immunité croisée est incomplète et que le virus reste intracellulaire pendant l'évolution de la maladie, il y a peu de chances que la vaccination soit efficace. La sélection de souches résistantes ne peut pas non plus être complètement efficace, car la résistance croisée est seulement partielle, et aussi parce que les virus semblent être assez facilement capables de produire des mutations chez les hôtes résistants.
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    Cellular and molecular life sciences 9 (1953), S. 333-333 
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    Notes: Zusammenfassung Aus den Abbauprodukten von Arborin und Dihydroarborin konnte für Arborin, das Hauptalkaloid vonGlykosmis arborea, die Formel eines 1-Methyl-2-benzyl-4-(1 H)-chinazolons erschlossen werden. Diese Formel wurde durch Synthese bestätigt.
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    Cellular and molecular life sciences 9 (1953), S. 340-340 
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    Notes: Résumé Des explantats ectodermiques de gastrulas deTriturus alpestris ont été soumis à des chocs thermiques dans des conditions variées; il ne s'est jamais produit de neuralisation des explantats, dont la basophilie était très faible. Il faut en conclure que la neuralisation des explantats ectodermiques ne se produit que lorsque les cellules ont été soumises à un type particulier de précytolyse.
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    Cellular and molecular life sciences 9 (1953), S. 287-287 
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    Notes: Summary On the occasion of the Swiss expedition to the Himalaya mountains, Ilford G 5- Nuclear Emulsion plates were brought up to an altitude of 8.000 m in order to measure the intensity of the nuclear component of cosmic rays. The number of stars obtained agree within the limits of error with other measurements at altitudes up to 5.000 m and above 25.000 m.
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    Cellular and molecular life sciences 9 (1953), S. 349-350 
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    Notes: Summary Green algae cultured for 24 days in a medium with addition of 1.3 butandiol or glycerol, showed reproducible changes of their fine structure, and an influencing of the cell number.
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    Development genes and evolution 146 (1953), S. 115-136 
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    Development genes and evolution 146 (1953), S. 183-200 
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    Development genes and evolution 146 (1953), S. 201-274 
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    Development genes and evolution 146 (1953), S. 403-406 
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    Development genes and evolution 146 (1953), S. 371-402 
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    Development genes and evolution 146 (1953), S. 407-420 
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    Development genes and evolution 146 (1953), S. 421-432 
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    Development genes and evolution 146 (1953), S. 433-486 
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    Development genes and evolution 146 (1953), S. 487-514 
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    Development genes and evolution 146 (1953), S. 544-579 
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    Chromosoma 5 (1953), S. 454-486 
    ISSN: 1432-0886
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    Notes: Zusammenfassung 1. In den somatischen Kernen vonCorixa punctata Illig. sind die homologen Chromosomen auf Distanz gepaart. In den mitotischen Prophasen findet eine vollständige Homologenpaarung statt. 2. Der Funktionszyklus der Epidermiszellen wurde besonders an den trichogenen Zellen untersucht. In jedem Larvenstadium durchlaufen die Zellen 2 Arbeitsphasen. In der 1. Phase wird vom Kern her unter Mitwirkung des Nukleolus die Bildung von Ribonukleinsäure im Plasma hervorgerufen; in der 2. Phase findet die Ausscheidung und Chitinisierung der Cuticula statt. Die Mitwirkung des Kernes ist außer an seiner Vergrößerung auch an dem Verhalten seiner Chromosomen kenntlich. In der 1. Phase sind die Chromosomen stark aufgelockert und entspiralisiert, in der 2. findet man in allen Kernen ein Auseinanderweichen von paarweise angeordneten Chromosomen unter zunehmender Entspiralisierung. 3. Die Kerne der trichogenen Zellen vergrößern sich unter Endomitosen. In jedem Larvenstadium findet höchstens eine Endomitose statt. 4. Die Endoprophase fällt in die 1., die Endoana- bis Endotelophase in die 2. Arbeitsphase der Zelle. Bei den Mitosen der Epidermiskerne fällt die Prophase ebenfalls in die 1. Arbeitsphase, Meta- und Anaphase werden rasch durchlaufen, aber die Entspiralisierung nach der Telophase wird bis zur 2. Arbeitsphase aufgeschoben. Nur die an die Spindel gebundenen Teilprozesse der Mitose sind also relativ autonom. 5. In Kernen trichogener Zellen, deren Chromosomen sich nicht teilen, machen die Chromosomen synchron mit denen der zur Endomitose schreitenden Kerne einen Formwechsel durch, der einer Endomitose ähnlich ist. Der Prozeß wird als Pseudoendomitose bezeichnet. 6. In polyploiden Kernen verhalten sich bei Endomitosen und Pseudoendomitosen die Schwesterchromosomen der letzten Endomitose so zueinander wie die Homologen in diploiden Kernen. 7. Die trichogenen Zellen, die von ihnen gebildeten Borsten und ihre Kerne wachsen mit jedem Häutungsschritt. Bei Überschreiten einer Größenschwelle folgt in den Kernen eine Chromosomenteilung. Die Endomitose wird also von der Zelle her ausgelöst. 8. Das mit einem Häutungsschritt verknüpfte Kernwachstum wird einerseits durch eine Endomitose gesteigert, andererseits ist es wahrscheinlich durch eine dem jeweiligen Chromosomenbestand entsprechende Maximalgröße beschränkt. Damit wird gezeigt, wie die Rhythmisierung des Kernwachstums durch Chromosomenteilungen vor sich geht. 9. Die Chromosomen der Kerne, die sich unter Endomitosen vergrößern, sind im frühen diploiden Kernzustand dicker als später im polyploiden Kern. Dabei, scheint ihr Durchmesser etwa der endgültigen Chromosomenzahl zu entsprechen.
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    Chromosoma 5 (1953), S. 428-453 
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    Notes: Zusammenfassung Anorganische Salze, Säuren, Basen sowie Urethane, Saponin, Zucker und Alkaloide und vergleichsweise auch Röntgenstrahlen wurden in ihrer Einwirkung auf die Meiosis vonOenothera untersucht. Die Betrachtung der Chiasmabildung und des Mutationsgeschehens erbrachte folgende Ergebnisse: 1. Anorganische Salze erniedrigen allgemein die Chiasmafrequenz nach Untersuchungen an der Diakinese. Dabei besteht keine Konzentrationsabhängigkeit, vielmehr genügt die Überschreitung einer bestimmten Schwelle, um eine Reaktion auszulösen, über die hinaus kein nennenswerter weiterer Erfolg mehr eintritt. Differenzen unter den gebotenen Stoffgruppen bestehen hinsichtlich der absoluten Höhe der Chiasmenfrequenz, denn Stickstoffverbindungen und Aluminiumsalze zeichnen sich durch auffallend kräftige Wirkung aus. 2. Die Konzentration der Wasserstoffionen hat keinen besonderen Einfluß und schwache Säuren und Basen, in ertragbaren Konzentrationen geboten, wirken schwächer als manche Neutralsalze. 3. Die organischen Verbindungen zeigen keinen besonders nachdrücklichen Einfluß auf die Chiasmenhäufigkeit, wohl aber besitzen, sie eine mehr oder weniger kräftige mutagene Wirkung. 4. Temperatur- und Schockversuche ergaben Veränderungen in der Anzahl der gebildeten Chiasmen, wobei die Länge der Intervalle und die Anzahl der applizierten Schocks eine Rolle spielen. 5. Für fast alle mutagenen Agenzien, anorganische wie organische Verbindungen und auch für die Röntgenstrahlen konnte eine auffallende Erhöhung der Streuung in der Chiasmenformation nachgewiesen werden, wobei die einzelnen Individuen eines Versuchs ein unterschiedliches Verhalten zeigen. 6. Paralleluntersuchung von Chiasmafrequenz und Mutationsrate an den reziproken Bastarden erbrachte keine gleichsinnige Veränderung der beiden Phänomene. Auch aus der Zusammenfassung aller 118 Versuche ergab sich keine Korrelation zwischen Chiasmenbildung und Mutationsgeschehen. 7. Es wird darauf hingewiesen, daß die Einwirkung von Chemikalien auf das komplizierte Stoffwechselgefüge einer lebenden Pflanze komplexe und vielfältige Reaktionen erzeugen kann, von denen sekundäre Einflüsse auf Chiasmenbildung und Mutationsgeschehen erfolgen können.
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    Chromosoma 5 (1953), S. 501-510 
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    Notes: Zusammenfassung 1. Die Paarungsaffinität der Riesenchromosomen vomSimulium sp. und vonBibio marci ist entlang der Riesen Chromosomen sehr verschieden stark ausgeprägt; die Verteilung der Paarungslücken ist keinesfalls zufällig. 2. Die Paarungsaffinität ist nach einer statistischen Prüfung von der Dichte der Scheiben unabhängig. 3. Zwischen Paarungsaffinität und der Entfernung vom Chromozentrum oder vom Chromosomenende besteht kein Zusammenhang. 4. Im heterozygoten Zustand von Inversionen bleibt auch innerhalb der Inversionsschlinge die regions-spezifische Paarungsaffinität erhalten.
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    Chromosoma 6 (1953), S. 142-148 
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    Notes: Summary and conclusions A small derivative of the standard type of B chromosome in rye was definitely demonstrated to be an iso-chromosome, (i) because both arms have the same chromomere structure, (ii) because the two arms of the same chromosome frequently pair with each other and (iii) because the four arms of a bivalent at pachytene may exchange partners with each other, forming a pseudo-tetravalent. The small iso-fragment is derived from the standard fragment because the arms have a chromomere structure identical to that of the short arm of the standard fragment. This identity implies (i) that the three main chromosome regions of the short arm of the standard fragment (cf.Lima-de-Faria 1952) are also present in both arms of the small iso-fragment, (ii) that the size and distribution of the chromomeres is the same and (iii) that the cone shaped terminal part of the short arm constituted by three chromomeres may be distinguished in both the mother chromosome and its derivative, the small iso-fragment. Owing to a high degree of meiotic elimination the frequency of transmission of the small iso-fragment is low even in plants with 2 such chromosomes.
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    Chromosoma 6 (1953), S. 149-169 
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    Notes: Summary The microphotometric two-wavelength method is demonstrated to permit, even with only an improvised optical set-up, DNA-measurements which would not be possible, at any rate not with a comparable accuracy, with the conventional method. The data, in agreement with earlier results, show that the largest interphase nuclei in the root meristem have already completed their DNA-synthesis. The mean DNA-contents per set of chromatids at late interphase, prophase, and telophase, appeared to be virtually identical. A natural variation in DNA-content, if any, between individual nuclei at these stage would have a coefficient of variation of significantly less, and most likely much less, than 7.3%. The data from metaphase to middle anaphase are, for technical reasons, not yet conclusive. An indicated, moderate, excess of Feulgen-dye in these as compared with earlier and later stages may not be real. The results are fully compatible with a working hypothesis of strict constancy of the DNA-content per chromatid and of its precise doubling during DNA-synthesis (for necessary qualifications see the discussion). It is pointed out that apparently contradictory results by certain other authors do not, for methodological reasons, yet establish disproof of this hypothesis.
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    Notes: Summary 1. The technique for making autoradiographs with stripping film is described in detail. Methods for administering P32 to plants and for preparation of tissues for autoradiographs are given. 2. Two different methods, enzyme digestion and acid hydrolysis, which were used for separating RNA, DNA, and phosphoprotein in tissue sections, were compared and evaluated. Although either method is valid for quantitative work, precautions are necessary and certain limitations to the quantitative separation of RNA and DNA should be taken into account. More work is needed to properly characterize the products extracted during enzyme digestion and acid hydrolysis. 3. Incorporation of P32 into nuclei of lily anthers was studied by the autoradiographic method at all stages from premeiosis to mature pollen. A quantitative comparison of the amounts of P32 extracted by RNase, DNase, Feulgen hydrolysis and hot TCA showed that incorporation into DNA occurred at relatively short periods during interphase, namely: (1) at preleptotene before meiotic prophase in microsporocytes, (2) at late interphase preceding mitosis in the microspore and (3) during early to mid-interphase in the generative nucleus of the pollen grain (the tube nucleus incorporates P32 slowly during the same period but this P32 was not definitely identified as DNA phosphorus). Two successive mitoses occur in tapetal cells while the microsporocytes are in meiotic prophase. In the interphase preceding each division incorporation of P32 into DNA occurs, but following the second mitosis no further divisions or incorporation was detected. However, during this latter period incorporation into RNA and phosphoprotein reached the highest level detected at any stage. During the period of DNA synthesis, incorporation of P32 into RNA was low or absent, but in the interval between the cessation of DNA synthesis and prophase the incorporation of P32 into RNA of both nucleus and cytoplasm reached its peak. 4. Microphotometric determination of amounts of DNA (Feulgen stain) showed that the amount per nucleus remains constant in all stages, except for doubling during the periods when P32 is incorporated, and the reduction by half at each division of a nucleus. The 2C amount is present in sporogenous nuclei until preleptotene when values intermediate between 2C and 4C are found. By the beginning of leptotene 4C is present in each microsporocyte nucleus. The amount does not change through meiotic prophase. Each nucleus after the first meiotic division contains 2C and each nucleus of the quartet of spores has 1C. The amount per nucleus in microspores doubles toward the end of the long interphase prior to prophase. After the mitosis in the microspore, the generative nucleus attains the 2C level relatively early in interphase. The vegetative nucleus has 1C in the interphase immediately after mitosis, but could not be accurately measured at later stages. Tapetal nuclei have the 2C amount of DNA when the microsporocytes are in leptotene. The amount doubles while the microsporocytes are in zygotene and the first mitosis usually occurs while the microsporocytes are in early pachytene. Another doubling occurs during the relatively short interphase and a second mitosis occurs when the microsporocytes are in late pachytene or early diplotene. The 4C class was typical for tapetal nuclei at later stages, but this may, in some cases at least, result from fusion of nuclei in the multinucleate cells during or following the second mitosis. 5. The periods of DNA increase (measured microphotometrically) coincide very closely with the periods of incorporation of P32 into DNA. This finding supports the concept of the stability of the DNA molecule, and indicates that incorporation may be used as a criterion not only of synthesis of DNA, but also of increase in the amount of DNA per nucleus.
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    Chromosoma 5 (1953), S. 199-220 
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    Notes: Summary Microdissection studies of the dividing neuroblast of the grasshopper,Chortophaga viridifasciata, lead to the following conclusions: 1. The spindle at metaphase is a semisolid body situated in a fluid cytoplasm; it consists largely of longitudinally oriented components; it appears to be attached at its poles to the adjacent region of the plasma membrane by weak astral fibers. From prometaphase through early anaphase the chromosomes are securely attached to the spindle at their centromeres. The spindle develops during prometaphase from the fluid karyolymph; during anaphase it undergoes liquefaction, which begins in the equatorial region and spreads poleward with or slightly in advance of the chromosome centromeres. By late anaphase the chromosomes at each pole are held firmly in a circle at their proximal ends. 2. The interzonal region of the anaphase cell consists of fluid protoplasm traversed by fine, invisible interzonal connections joining the distal ends of sister chromosomes. Its elongation during anaphase is an intrinsic process that is independent of any attachment of the spindle to the adjacent cell membrane by astral rays and appears to be responsible for much of the anaphase separation of sister chromatids. 3. Early anaphase separation of sister chromatids begins at the centromere and progresses distally. 4. Polarization of the neuroblast is largely independent of the spindle and chromosomes. 5. Formation of the cleavage furrow is independent of the spindle and chromosomes, but its position depends to a limited extent on their position at late anaphase.
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