Gametogenesis in Cestodes. 
429 
it frequently elsewhere. But in no case whicli I have seen is this skein 
(“synapsis”) stage followed by tlie succeeding stages of mitoses, the eggs 
always entering the uterus in the resting condition. This disappearance 
of the skein has been described by both Child (1907,111), Janicki (1907), 
Richards (1911), and Harmax (1913), who says (p. 214), speaking of the 
“post-synaptic” changes in the ovary, “This change in the chromatin 
goes on until it forms a finely granulär reticulum . . . (and) remains in 
this condition during the remainder of the growth period.” 
Fertilization, which is very difficult to observe in cestodes, has been 
described by Child (1. c.) in Moniezia and myself (1. c.) in Taenia pisiformis, 
and I have nothing here to add to these accounts. The egg, when it enters 
the Uterus, is in the resting condition, and fertilization soon occurs, if it 
has not already done so in the oviduct, as is evidenced by the appearance 
of two pronuclei. 
At this time mitoses occur very frequently, as is generally admitted 
by those who have studied this question. The interpretation of these 
mitoses is not however an easy matter, and has led me in an earlier paper 
(1. c.) to a view which is widely divergent from that of other writers. They, 
in accordance with usual custom, admit the occurrence of polar bodies 
in cestodes, and find in these mitoses evidence of the customary two matu- 
ration divisions, prior to the union of the germ nuclei in fertilization. 
There is no agreement however among these authors, as to what constitutes 
the polar bodies, nor have they given any satisfactory evidence of a rela- 
tion between these mitoses and the structm’es which they assume to be 
polar bodies. Nor yet have they given any satisfactory account of the 
all-important process in matmation, namely cliromosome reduction, or 
any satisfactory criterion for distinguishing between first and second 
maturation divisions, or even between a maturation and a cleavage mitosis. 
Child and Richards interpret a yolk cell as a polar body, and apparently 
Harmax has fallen into the same error, altho her description of maturation 
is too brief, and her figures too unsatisfactory, in this respect, to admit 
of certainty as to what structure she did identify as a polar body. Janicki 
(1907), proceeding more cautiously with Leuckarts work in mind, has 
endeavored to identify as polar bodies certain minute, densely staining 
structures lying on, or near the surface of the egg, and in suitable relation 
to the mitotic spindles, while very similar bodies, lying within the egg, 
and apart from the spindles he identifies as “?’s”, altho there is no apparent 
distinction between them, save that of position. 
I have taken the whoUy unorthodox position that both the spireme 
in the ovaiy and the spindles in the uterus represent an abortive attempt 
