PLATE 7 



EXPLANATION OF FIGURE? 



All figures X 681 



62 Primordiimi of goniduct in specimen Ij to I5 mm. long. Figure drawn 

 at proximal end of strand, where latter joins gonad. Optical section. 



63 Slightly later stage, showing appearance of lumen in middle of strand. 

 Optical section. 



64 Higher focus at same place as figure 63, showing surface of duct. 



65 Later stage, showing the flattening of the walls and the nuclei within 

 them. Gonad of specimen contained spermatogonia, some of which have got 

 into the goniduct. 



66 Proximal part of the goniduct of specimen where rapid spermatogonial 

 multiplication was taking place in gonad. Duct enlarged and slightly twisted 

 upon itself. Cilia appearing. Length of specimen, 8 mm. Penis partly de- 

 veloped. 



67 Section through one turn of seminal vesicle in specimen having nearly 

 mature testis. A few sperm have been formed and reached the seminal vesicle. 

 Length of specimen, 5 mm. 



68 Distal part of goniduct (vas deferens) in same specimen as above. 



69 Section of small part of wall of seminal vesicle in specimen with de- 

 generate testis, showing entrance of sperm head into wall. Length of specimen, 

 11 mm. 



66 



