428 
R. T. Young 
If however the uucleus does not in general pai'take dii'ectly in sperm 
development wliy is it that the latter is usually found closely associated 
with, if not directly attached to the former. This often is not evident 
in fixed material, but is generally so in fresh. In figs. 20, 23 and 24, 1 have 
illustrated typical cytophores from Taenia pisiformis and teniaeformis 
which illustrate this. In fig. 23 the earliest stage of sperm development 
is shown. Here the cytoplasm of the spermatid is drawn out into a short 
thick pencil, but there is little evidence of nuclear elongation, and none 
of nuclear condensation accompanying it. In fig. 24 is shown a slightly 
later stage, in which the sperm has elongated and thinned out materially, 
but without any corresponding change of the nucleus. A stiU later stage 
is shown in figure 20 which is a free hand drawing of a cytophore from Taenia 
pisiformis. Here the sperms are probably nearly mature. They show 
a slight swelling at the future head end, but no other differentiation; nor 
is there here any evidence that the nucleus will form a part of the adult sperm. 
The same general relation is seen in Khyncobothrium (fig. 16) tho here, 
as already noted, the number of attached sperms varies from one to three or 
possibly more. Here however the sperms occasionally terminate, not in the 
nuclei, but in granules in the cytoplasm, as is shown in fig. 17, 28 and 29. 
Two possible explanations of this relation occur to me. One is that 
the secondary nuclei and the spermatozoa arise more or less simultane- 
ously and coincidentally in the same region of the cytophore; while the 
second is that the nucleus Controls the development of the sperm, altho 
not directly forming pai't of it. 
2. Gametogenesis, 
a) Deyelopment of the ovarj. 
Apart from purely anatomical differences of form and position the 
early development of the ovary is similar to that of the testis. Both de- 
velop from undifferentiated parenchyma and the method of ceU division 
is similar in each. Here however no cytophore is formed altho occasional 
polynucleate cells occur (fig. 2), while the growth of the oogonia is con- 
siderably greater, and the resulting oocytes considerably larger than is 
the case with the corresponding elements in the testis. 
b) Development of the oocytes and the occurrence of abortive 
matnratiou divisions. 
Following, or during the growth of the oocytes their nuclei may 
develop a skein, altho this is not always evident. I have previously (1. c.) 
described and figm’ed this stage in Taenia pisiformis and have observed 
