144 TOKIO KABURAKI 
from the accumulations of the mother-cells he some compact 
masses of metamorphosing spermatozoa. The spermatoblast 
in a further stage of development presents an elongated, pear- 
shaped protoplasmic body, in the broad end of which the 
nucleus is visible as a distinct, deeply staining spot. It is then 
changed into a spermatozoon, the nucleus forming the head and 
TEXT-FIG. 4. 
| 
' 
( 
H 
od va 
Diagrammatic representation of the genital organs of Rh. ceylonicus 
von Graff. gv.—genital vestibulum. Other letters as in Text-fig. 1. 
the protoplasm having greatly stretched out and elongated 
itself into a thin thread to form the tail of the spermatozoon. 
Each testis gives rise, on its lower side, to a short canal which 
communicates soon with the vas deferens. The vasa deferentia, 
proceeding backwards close along the dorsal sides of the longi- 
tudinal nerve cords, rise obliquely upwards to enter, each 
separately, the bulbous part of the penis at the upper lateral 
sides, and finally open into the lumen of the penis or the seminal 
vesicle. The vas deferens, which is filled with spermatozoa, is 
