216 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



One copulation apparently fertilises all the eggs pro- 

 duced by the female. It is obvious, when one compares 

 the male with a mature female (Plate I., figs. 1 and 2), 

 that fertilisation cannot be accomplished when the female 

 genital segment is fully developed. Hence the need of 

 it being effected at an early stage. 



The exact period at which the eggs are fertilised by the 

 spermatozoa is unknown. The spermatophores may be 

 found attached to the body for some time after the female 

 has begun to produce eggs (Plate II., fig. 4, sp.), but they 

 are then simply empty sacs. Plate II., fig. 7, shows a 

 pair of spermatophores that have been detached from an 

 egg-bearing female. The little opening at d. was in 

 direct communication with the vulva. These sacs were 

 empty. In an immature female (Plate II., fig. 6), the 

 vulva leads into a short vagina, passing directly into the 

 oviduct. The spermatozoa probably remain in the vagina 

 which becomes a " receptaculum seminis." In transverse 

 or longitudinal sections through the region of the vagina 

 of a mature female masses of spermatozoa are frequently 

 found in the swollen part (Plate II., fig. 4, rep.). The 

 oviduct in the immature female has no communication 

 with the exterior except through the vulva. 



The ovary of a mature female appears as shown in 

 Plate II., fig. 10. It consists of a number of tubules 

 lined with nucleated cells representing a germinal epithe- 

 lium, which will form the eggs. The interior of the 

 tubules is filled with a granular substance, staining faintly 

 blue with hematoxylin and eosin. When the eggs become 

 mature the walls of the tubule break down and the eggs 

 pass out into the oviduct. They are then very small, about 

 •02 mm. in diameter, and do not fill up the duct. They 

 are simply nucleated cells. As they pass posteriorly they 

 increase in size. In the fourth thoracic segment they 



