1902.] NICHOLS — SPERMATOGENESIS ONISCUS ASELLUS LINN. 97 



The large cells lining the vas deferens are described and also 

 the smaller cells between them. The latter are believed to arise 

 from the larger ones by segmentation. The function of the large 

 cells is said to be the secretion of the fluid which bathes the sper- 

 matozoa. The nucleus of these cells is figured as a network of 

 great regularity. 



The mature colony of Asellus, as figured by Gilson in Vol. 2 of 

 La Cellule, PI. X, Figs. 385-395, agrees with that of Oniscus in 

 general appearance. The spermatozoa in the bundle, however, are 

 more numerous and much less compactly bound together. Asso- 

 ciated with them in their development is a large cell (''noyau 

 femelle "). The tail is shown to be distinctly continuous with the 

 nucleus. The granular mass surrounding the nucleus at its free end 

 is said to consist of caryoplasm and the remains of the nuclear 

 membrane. Its formation is shown in Figs. 387-393. 



A few figures are also given of Idotea. 



1886. Wielowieyski, in a short paragraph concerning Asellus, 

 states his opinion that the ''noyau femelle" of Gilson is an artifi- 

 cial product, caused by the confluence of the protoplasmic mass with 

 one of the large cells on the margin of the testicle. 



Cirrepedli. 



1886. Gilson figures the spermatozoa of Lepas anatifera and 

 Balanas perforatus. They are flagellate, the nucleus a slender 

 thread occupying the anterior end. 



1894. Ballowitz, K., studied Balanas improvisus Darw. and Lepas 

 anatifera L. He makes the astonishing statement that the head is 

 demonstrable as a distinct structure neither by its form nor by its 

 staining reaction. He mentions the work of Nussbaum (1890) on 

 a Californian Cirrepede (Pollicipes polymerus) in which the head 

 is described. 



Copepoda. 



1895. Steuer gives a figure to show the spermatozoa of the 

 marine Copepod, Sapphirina gemma. They are flagellate, shaped 

 somewhat like a javelin. He mentions the spermatozoa of the 

 Calanidse as being of spherical shape. 



Osiracoda. 



1886. Stuhlmann. The spermatozoa of the Cypridae are de- 

 scribed as having at first the shape of a ribbon, through the length 



PROC. AMER. PHILOS. SOC. XLI. 168. G. PRINTED MAY 8, 1932 



