618 NATHAN FASTEN 



immunis do not confirm this. On the contrary, all the evidence 

 tends to the conclusion that the arms of the spermatozoon are 

 derived from the cytoplasm and that the nucleus forms the head- 

 like mass in the cytoplasmic bowl, opposite the transparent 

 vesicular cup. These observations, moreover, are in accord 

 with those of most other investigators on decapod spermato- 

 genesis, namely, that the rayed arms of the sperm are of cytoplas- 

 mic origin. 



The final stage in the development of the spermatozoon is 

 the winding of the radiating arms about the combined cytoplasmic 

 and nuclear cup. The rays become tucked around this cup and 

 conceal it (fig. 67, R) . They must be supplied with a transparent 

 adhesive substance which attaches them firmly, thereby effacing 

 their outlines. In this stage the entire spermatozoon stains 

 lightly a^d almost uniformly. Figure 67 gives a side view of a 

 mature spermatozoon within one of the tubules of the testis, 

 showing the invaginated vesicle, V, set into a cup consisting of 

 the nucleus and the radiating arms. The nucleus, A^, cannot 

 be seen because the arms, R, surround it and hide it from view. 



During the breeding season almost all the tubules of the testis 

 and the ducts of the vasa deferentia contain these ripe sperma- 

 tozoa in enormous numbers (figs. 78 and 81). They all seem to 

 be translucent, spheroidal bodies (fig. 68), consisting of a re- 

 fractive vesicular cup (figs. 68-70, V), set into a larger watery- 

 looking ellipsoid (figs. 68-70, R), which contains a somewhat 

 denser granular mass, with a large globule (figs. 68-70, X) in 

 its bottom. Figures 68 to 70 are camera lucida drawings of 

 living spermatozoa studied in Ringer's solution. Figure 68 is a 

 side view, whereas figure 69 is a top view. Figure 70 is a side 

 view showing the opening up of the spermatozoa. After copu- 

 lation in autumn, the females have their seminal receptacles 

 stocked wdth these spermatozoa. 



One can get a very good idea of the mature, uncoiled spermato- 

 zoon by imagining an inverted bowl with its wall invaginated 

 at the mouth and turned back into the cavity, fitted into a foot- 

 ball of about twice its size at the laced end. The bowl would 

 correspond to the refractive vesicle (figs. 67-68, V) , and the foot- 



