158 
R. T. Young 
scendants arose by the direct division of the entire parent body; but rather 
as a collection of nutritive substance to serve as a reserve supply for the 
cell. There is little doubt that the nucleus does perform this function 
in the cell today, as is shown by those experiments in which cells have 
been divided into nucleate and non-nucleate parts, the former surviving 
the Operation and the latter perishing. That, during the course of evo- 
lution, the nucleus should have also assumed the function of transmit- 
ting the hereditary properties of organisms is entirely possible, altho not 
proven as yet. In the Cestodes, however, in connection with their general 
degenerate character, it is by no means impossible that the nucleus should 
have lost any such function that it may have possessed in the ancestors 
of this group, retaining only its primitive character as a nutritive body 
for the supply of the cell. It is further possible in connection with such 
degeneracy that the nucleus should have returned to its primitive meth- 
od of origin as a modification of undifferentiated protoplasm. 
Certain cytological phenomena in Cestodes suggest that the mitotic 
process at least has degenerated in this group, even tho my view as to 
the de novo origin of nuclei be not admitted. These facts are the more 
common occurrence of mitoses in the development of the germ cells 
(Child 1907. a, b, c, d) in Moniezia than at other times. This suggests 
that we have in the earliest stages of development a recapitulation of 
processes existent in the ancestors of the group, which processes have 
practically disappeared in later stages. In Taenia serrata, as .1 have 
already noted (1. c., p. 245) and as I hope to show at greater length in 
a forthcoming paper, I have found abortive mitosis occurring commonly 
in gametogenesis. But, while I have here found numerous mitotic pro- 
phases, I have found comparatively few of the later stages in this 
process and I believe that they are disappearing in this worin 1 ). 
I believe further that we have proceeding before us today in Cestodes 
not only the degeneration of mitosis 2 ) but also of any nuclear division 
whatever, the final result of such degeneration being the de novo 
origin of nuclei as described. I have found many probable instances of 
amitotic divisions of nuclei in several of the forms studied. In one of 
these, indeed, Rhynchoibothrium bulbifer, this method of nuclear multi- 
*) I make tliese Statements with the reservation that my studies on the gameto- 
genesis of Taenia are preliminary, not final, as yet. 
2 ) A summary of nuclear counts made in this investigation and the correspond- 
ing number of mitoses observed shows the following result: 
Total number of nuclei counted 33930. 
Total number of mitoses observed 50 (7 of which were verv doubtful cases). 
