683 
derm geliefert werden, wie das ja auch für die Säugetiere ohne Zweifel 
der Fall ist und noch neuerdings von KrıBEL!) besonders hervor- 
gehoben wurde. Mit dieser Uebereinstimmung hinsichtlich der Ent- 
stehung des definitiven Darmepithels bei Säugern und Reptilien fällt 
gleichzeitig das wichtigste Bedenken hinweg, daß sich dem letztge- 
nannten Forscher bei Anwendung der von VAN BENEDEN, RABL und 
mir vertretenen Gastrulationstheorie auf die Säuger in den Weg stellt. 
Rostock, den 8. Juli 1893. 
Nachdruck verboten. 
Mammalian Spermatogenesis. 
(From the Huxley Research Laboratory, Royal Coll. of Science, London.) 
By Joun E. 8S. Moors, A, R. C. 8. 
With 4 Figures. 
In a recent number of this journal Dr. FırLn gave an interesting 
account of the spermatogenesis in Echinoderms. He finds that the 
spermatozoa arise from the “spermatogenes” after two successive 
mitoses in which there is a reduction by one fourth in the number 
of the chromatic elements, and that the “Nebenkern” and centrosomes 
existing in the cells which give rise to the spermatozoa are incorporated 
as an essential part of the spermatozoa themselves. 
The Nebenkern he believes to have the same value that PLATNER 
ascribed to it in the spermatocytes of Helix, or that it is a coalescence 
of the spindle fibres, a relation which I showed some months ago to 
be the explanation of the changes witnessed in the similar body existing 
in the genital cells of Salamander and described indifferently there, as 
Archoplasm, Nebenkern or Attraction sphere. 
I now wish to extend this view and to show how close a parallel 
exists in other respects between the spermatogenesis of Echinoderms, 
as formulated by Dr. Freip, and a spermatogenetic scheme I have been 
able to construct by a similar process of comparative study of the 
1) F. Kerset, Studien zur Entwickelungsgeschichte des Schweines 
(Sus scrofa domestisus), mit 6 Tafeln und 29 Holzschnitten, in: Morphol. 
Arbeiten, Bd. III, 1893. 
