STUDIES ON SEX IN CREPIDULA 43 



Two new conditions may now be observed in that part of the 

 goniduct which was formerly the seminal vesicle. In the first 

 place, cell outlines begin to appear between the nuclei, dividing 

 the cytoplasmic wall into high, irregular cells which make up a. 

 columnar epithelium. Secondly the cytoplasm of these cells be- 

 comes less dense than was the cytoplasm of the vesicle wall, 

 and in the most transparent regions are clusters of granules (fig. 

 76), indicating some change in the cytoplasm. The appearance 

 of these granules recalls a somewhat similar condition in the 

 wall of the gonad after the testis has degenerated (figs. 47, 48). 

 Cilia begin to appear again in the proximal part of the goniduct 

 (figs. 75, 76), the cell outlines become more and more distinct 

 (fig. 79) and the cytoplasm more and more transparent (figs. 

 79, 80). The remains of the seminal vesicle no longer show any 

 twisting, and the whole goniduct runs almost straight to the 

 gonad. Cell outlines may be seen in the distal part of the duct 

 (figs. 77, 78) as well as in the proximal. 



In discussing accessory male organs it has been said that they 

 never appear until the development of the testis is under way. 

 Contrasted with this, certain accessory female organs begin to 

 develop before the gonad exhibits any sign of development to 

 an ovary. The formation of the uterus, for instance, is more or 

 less independent of the sexual condition; it often begins in large 

 sexually inactive animals, or even in very large males. The 

 goniduct also sometimes assumes the appearance of an immature 

 oviduct in large neuters. None of the accessory female organs 

 take on their adult condition, however, until the oocytes are 

 well advanced in the growth period. 



During the growth of the oocytes, which lasts for a consider- 

 able time, the body of the animal is also growing rapidly, if not 

 subjected to a dwarfing environment. The oviduct is increased 

 enormously in size, though in comparison with the length of the 

 animal it is shorter than the male goniduct. Figure 81 shows a 

 cross section of the distal part of it at a time when the oocytes 

 are in the process of yolk formation. Comparison with figure 

 77 gives an idea of the amount of growth since the stage last de- 

 scribed. The walls have been thrown into longitudinal folds 



