I5O A. RICHARDS. 



details not bearing upon the point which I wish to consider) 

 the criterion of proliferation seems to be smallness of nuclei, 

 although in the figures illustrating these statements constricted 

 nuclei, amitoses, are present. As previously stated, these regions 

 in my sections do not show amitoses. But mitoses are to be 

 seen (rarely, it is true) in the borders of the proliferating region. 

 The presence of mitotic figures in this region, it seems to the 

 present writer, is a most significant fact where but in the borders 

 of a region which is extending its area should division figures be 

 found? and the small size of the nuclei at the center is of little 

 importance. These central cells are merely beginning differen- 

 tiation while the proliferation takes place at the periphery of the 

 sex duct anlage. 



The method of cell multiplication in the female sex ducts of 

 Moniezia cannot at the present time be positively stated. I find 

 no certain evidence for amitosis and that for mitosis is, perhaps, 

 insufficient to account for the growth which has taken place. 

 Nevertheless, I have seen some cases of mitosis here. 



Fertilization and Maturation. The process of fertilization in 

 the eggs of Moniezia can be followed only with the greatest dif- 

 ficulty. Although one may examine carefully a great number of 

 proglottids he will rarely find a stage showing the entrance of 

 the sperm and its course prior to the maturation divisions. I 

 am, therefore, unable to amplify the account given by Child 

 ('oje) of the early stages of fertilization. 



From the ovary the passage through the oviduct to the uterus 

 is so rapid that eggs are seldom found in that part of the duct. 

 Linton ('08) has observed the process of fertilization in a live 

 trematode, and found it to be of very short duration (less than 

 40 seconds) . In Moniezia one often finds segments with embryos 

 in the uterus undergoing maturation and eggs in the oviduct 

 ready for fertilization, but the cases are rare in which there are 

 eggs in the fertilization duct. Doubtless here also the passage 

 is very rapid and probably, as Child thinks, periodical. 



The eggs pass from the ovary into the uterus through a more 

 or less coiled oviduct. They meet the spermatozoa at the mouth 

 of that branch of the oviduct which comes from the seminal 

 receptacle and are there fertilized. Near this point the vitello 



