163] LIFE HISTORY OF GORDIUS AND PARAGORDIUS—MA Y 43 



into the seminal receptacle. The large muscle surrounding the posterior 

 part of the gland has been described under the topic of cloacal musculature. 



The seminal receptacle extends forward as an elongated sac with defi- 

 nite walls similar to those of the oviducts at their posterior ends. It is 

 empty and distended, occupying in cross section fully one half the diameter 

 of the body and extending lengthwise over a space equal to three or four 

 times that diameter. The intestine passes around to the ventral side of the 

 body before the end of the seminal receptacle has been reached. 



The testes in the males remain as cylindrical or somewhat triangular 

 tubes extending nearly the whole length of the body (Figs. 72, 80, 107, 108). 

 They are enclosed in heavy membranes and very early become completely 

 surrounded by parenchyma cells. As in the ovaries so in the testes there are 

 never any traces of cellular walls. 



At the anterior end the testes are subject to bead formation similar to 

 that in the ovaries. The sperm ducts are posterior extensions of the testes, 

 opening into the intestine a short distance anterior to the anus, and in the 

 early stages in no way distinguishable from the testes (Figs. 29, 70-71). 

 Cellular walls for the sperm ducts are formed only within the cloacal mus- 

 culature, anterior to that all of the cells develop into spermatozoa. 

 The intestinal diverticula as in the case of the females consist of nothing 

 more than a turning out of the walls of the intestine at those points. 



The transformation from spermatocytes to spermatozoa begins at a 

 slightly later stage in development than does the growth of the oocytes in 

 the female. It takes place almost simultaneously in all parts of the testes 

 and is completed before the adult cuticula has been fully formed. 



The chromatin rod appears as a semicircle at one side of a rounded cell, 

 but later becomes straightened and takes up a median position while the 

 cell becomes spindle-shaped. At the same time the cytoplasmic contents 

 pass to one end leaving the rod at the other end surrounded by only a 

 thin layer of cytoplasm, the thickest part of the spindle being either at or 

 even beyond the end of the rod (Figs. 12, 13, 18, 19). In this form the sper- 

 matozoa leave the male. Before they pass into the body of the female they 

 become somewhat elongated (Fig. 10). In the seminal receptacle of the 

 female the cytoplasmic part of the spermatozoon elongates into a heavy 

 flagellum of uniform diameter while the rod remains as a slightly thickened 

 head at one end (Fig. 17). 



