a few loops of the chromatin remain behind in the middle and form a 

 cytophore. The cytophore can persist for some time, eventually all trace 

 of its nucleus disappears, the protoplasm changes its reaction, staining 

 orange, and finally it disappears when the spermatozoa mature. 



I have not been able to compare with any data given by other 

 observers than those quoted, owing to inaccessibility of the literature. 



Further Development op the Female Organs. 



The Oogenesis in Stilesia would be doubly interesting to follow, for, 

 owing to the absence of viteUine glands, it differs from that of most other 

 cestodes. 



In the earliest stages the ovarian nuclei form a syncytium and divide 

 amitotically as described by Child for Moniezia ; the first mitoses were 

 observed at about 50 cm. from the scolex, at a stage at which the oviduct 

 and uterus were yet solid masses of tissue without apparent lumen. 



At this stage, the cell boundaries are becoming distinct. As develop- 

 ment progresses, mitoses become more frequent, and finally all cell division 

 appears to take place by mitosis. In the ripe ovary (80 cm. from scolex) 

 mitoses are frequently observed, four chromosomes appearing to be the 

 normal number. In the case of the ovarian ova, the resultant cells seem 

 to separate as soon as the mitosis are over. Mature ovarian ova measure 

 approximately 20 fi X 16 ^4; their nuclei are round and about 8 /^ in diameter. 

 Fertilisation probably takes place in (the oviduct or) the uterine duct. 

 The passage of eggs through the ovi-uterine duct must be a very quick one, 

 as in no case have I found an ovum traversing either of the two ducts; 

 this although many segments have been examined on sections in stages 

 in which the ovarium is in full function, and the uterus is filling with ova. 



Arrived in the uterus mitoses commence again, but the resultant 

 nuclei remain embedded in a syncytium ; such cells with two or four 

 nuclei are very common ; the number of chromosomes seems to have 

 increased — I believe that there are eight — but they are very difficult to 

 count ; in any case four is no longer the normal, but a higher number is 

 always present. Young uterine ova measure approximately the same as 

 the mature ovarian ova, their nuclei however decrease in size as division 

 progresses ; two in one young ovum measured 6 ,« in diameter. It may 

 here be stated, that I have sometimes found ova similar to those in the 

 ovary or to those just arrived in the uterus, free in the parenchym of the 

 body, occasionally in large numbers. Just at this part, my material 

 is unfortunately not sufficiently well preserved to enable the further 

 changes to the ova to be followed in detail. 



The maturest ova which I have seen have a thin membrane, and 

 lie in egg-pouches, no longer in the uterus. 



After the stage at which fertihsation takes place, several changes 

 occur in the female genitalia ; in the first place a layer of dense fibrous 

 supporting (or connective) tissue is formed anteriorly to each uterus. 



