Fortpflanzung, 79" 



181) Meisenlieimer, J. (Jena, Zool. Inst.), Über die Wirkung von Hoden- 

 und Ovarialsubstanz auf die sekundären Geschlechtsmerkmale des 

 Frosches. In: Zool. Anz. 38, 2, S. 53—60, 5 Fig., 1911. 



Die Kastration männlicher Frösche hat eine fast vollständige Reduktion der 

 Daumenschwiele zur Folge, die aber durch nachfolgende Implantation von Hoden- 

 substanz in die subcutanen Lymphräume wieder aufgehoben werden kann. Merk- 

 W'ürdigerweise vermag auch implantierte Ovarialsubstanz bei kastrierten Fröschen 

 die Entwicklung der Daumenschwiele wieder anzuregen. Meisen heimer zieht 

 aus diesen experimentellen Befunden den Schluß, daß es sich hierbei nicht um 

 einen spezifischen Einfluß der Geschlechtsdrüsen auf die sekundären Sexual- 

 charaktere, sondern nur um einen ganz allgemeinen Einfluß auf den ganzen Stoff- 

 umsatz des Körpers handele. F. Fax (Breslau). 



182) Smith, Geoftrey and Schuster, E. (Oxford, Universitj^), Studies in the 

 Experimental Analysis of Sex. Part. 8. The Effects of theRemoval 

 and Transplantation of the Gonad in the Frog (Rana fusca). In: 

 Quart. Journ. Micr. Science 57, 4, S. 439 — 471, 4 plates, 1912. 



The cyclical changes in the testes and thumb of male frogs are described. 

 Transplantation of the testes into other individuals, male or female, leads to de- 

 generation of the testicular tissue. Testes severed from their connexions, but left 

 in the same individual, show degeneration of the ripe spermatozoa, but the 

 spermatogonia survive and proliferate. Ovariotomy, with or without subsequent 

 implantation of testes or injection of testis extract, does not cause the thumb 

 of the female to assume any male characters. Castration of the male, except in 

 the breeding season, has little or no effect on the thumb-characters. Castration 

 in the breeding season is followed by rapid throwing-off of the outer papillated 

 layers of the thumb-pads. Implantation of testis, and injection of testis-extract, 

 has an entirely negative effect on the thumb of castrated frogs. The opposite 

 results ofNussbaum and Meisen heimer are criticized, and it is concluded that 

 there is no evidence of an internal secretion, which, injected into a castrated 

 frog, causes increase of the thumb-papillae. Doncaster (Cambridge). 



183) Marshall, F. H. A. (Cambridge, University), On the Effects of Ca- 

 stration and ovariotomy in sheep. In: Proc. Royal Soc. Vol. B. 85, 

 No. 576, S. 27—32, 1912. 



The author summarizes his work as follows: — "(l) The development of 

 horns in the males of a breed of sheep in which well-marked secondary sexual 

 differentiation occurs (as manifested especially by presence or absence of horns) 

 depends upon a Stimulus arising in the testes, and this Stimulus is essential not 

 merely for the Initiation of the horn-growth, but for its continuance, the horns 

 ceasing to grow whenever the testes are removed. (2) The removal of the ovaries 

 from young ewes belonging to such a breed does not lead to the development 

 of definitely male characters, except possibly in an extremely minor degree."^ 

 (Very small 'scurs', or projections appeared on the skulls of the ewes from which 

 ovaries were removed; no such appeared on the skulls of the control ewes.) 



Doncaster (Cambridge). 



Hierzu: Nr. 122, 124, 141, 187, 193, 194, 203, 235, 249, 254, 258, 260, 261, 271, 288—291^ 

 300, 306, 307, 319, 333, 335, 336. 



