7 Fortpflanzunor. 



Fortpflanzung. 



158) Burghardt, R., Zur pathologischen Anatomie des Stuteneier- 

 stockes. In: Archiv für wissensch. u. prakt. Tierheilk. Bd. 37, Heft 5, S. 455 

 bis 508. 1911. 



Der Pferdeeierstock unterscheidet sich dadurch von dem anderer Tiere, daß 

 das Keimepithel sehr bald zugrunde geht. Dem Pferdeeierstock ist außerdem 

 eine besondere pigmentierte Zellart eigentümlich, die Keimlagerzellen, die eben- 

 falls, aber allmählich verschwinden. Infolge des Zugrundegehens dieser Zellen 

 findet eine Hypertrophie des Bindegewebes ex vacuo statt, so daß schließlich der 

 ganze Eierstock ein fast rein bindegewebiges Gefüge hat und nur wenig Paren- 

 chym enthält. Die übrigen Angaben beziehen sich lediglich auf pathologisch- 

 anatomische Beobachtungen. Pfeiler (Bromberg). 



159) Riddle, Oscar, A Gase of Yolk Formation Not Gonnected with 

 the Production of Ova. In: Biol. Bull. XXII, Nr. 2, January 1912, S. 107 

 —111, 1 table. 



The author demonstrates the formation of yolk in the walls of emptied cap- 

 sules of hens' ovaries. The site of formation is not in the interior of the capsule, 

 but within its wall external to the foUicular epithelium. The chemical composi- 

 tion is entirely similar to that of normal yolk, but with higher ash content and 

 lower protein content. In this case then the production of yolk, often in con- 

 siderable amount, is accomplished by the cells of the theca externa. 



Lillie (Ghicago). 



160) Bragg, L. C. and Bragg, L. B., Spermatogenesis, or Origin of the Male 

 Germ Cells. In: Amer. Breeders' Mag. Vol. II, pp. 220—222, 1911. 



Populär. Of no significance whatever to the investigator. Pearl (Orono). 



161) Doncaster, L. (Cambridge University), The Ghromosomes in Ooge- 

 nesis and Spermatogenesis of Pleris hrassicae. In: Proc. Cambridge 

 Philosoph. Soc. 16, 6, S. 491—492, 1912. 



There are 30 oogonial chromosomes; in the oocyte after synapsis (synizesis) 

 there are 14 chromatin threads and a double chromatin-nucleolus. The threads 

 contract to 14 double chromosomes. In the first spermatocyte division there 

 are 15 chromosomes all of which appear to divide equally. In the second divi- 

 sion there are also 15, and although there are some size-differences between 

 different figures, there is no sufficient evidence for the existence of an unequally 

 paired heterochromosome. In each sex there are thus 15 pairs of chromosomes, 

 one of which takes the form of a double chromatin-nucleolus during the growth- 

 phase. Doncaster (Cambridge) 



162) Stevens, N. M., Supernumerary Chromosomes, and Synapsis in 



Ceutoplnlus (sp.?). In: Biol. Bull. XXII, No. 4, March 1912, S. 219—230, 

 36 figs. 



1. In one specimeu one and in another two supernumerary chromosomes 

 were found. There is an unpaired X dement which passes undivided to one pole 

 of the spindle in the first maturation division and divides in the second division. 

 The behavior of the supernumeraries is irregulär; they may or may not divide 

 in the first maturation mitosis, and they may, when undivided, go to either pole 

 of the spindle. Their origin is in doubt, but they are probably related to X. 



2. The synapsis is a very clearly side by side (parasynapsis). During this 



