Young, Cytology of Cestoda. 3gg 



(1856) and von J a n i c k i (1907), to which latter Interpretation 

 I adhere, all apparently refer to the same cell. 



My reasons for this belief are as follows: 



Its nucleus is similar to that of the yolk cells, which are occa- 

 sionally fovmd free in the uterus among the developing eggs. 



Occasionally considerable masses of yolk may be found in 

 it after its attachment to the egg. p 



Its number varies from one to two. 



The rarity of anaphases and absence of telophases in maturation, 

 noted both by myself and others, and the spindle degeneration 

 while the equatorial plate is still formed, renders the occurrence 

 of polar bodies very doubtful. 



The further fate of this cell is very interesting. It soon be- 

 comes greatly distended by masses of food bodies present in the 

 tissues of the proglottid, and evidently serves as a nurse for the 

 growing embryo. It is eventually cast off as described by St. 

 R e m y (1901). 



In a total of 33,930 nuclei counted 1 ) in the Cestode soma, 

 mainly in actively growing regions, I have observed only 50 mitoses, 

 most of which occured in Anoplocephala sp., and none of which 

 were later than the metaphase, most ot them being prophases. 

 Many cases of probable amitosis occur 2 ). 



Summary. 



Corresponding to the otherwise degenerate condition oi 

 cestodes, mitosis is also degenerating, but few remnants remaining, 

 these occurring chiefly in gametogenesis and cleavage. The former 

 of these processes is also degenerating, maturation being abortive 

 both in ovo and spermatogenesis. The nucleus arises either de 

 novo or amitotically, while mitosis occasionally occurs. The 

 nucleus is a physiological, not a morphological structure. 



Literature cited. 



Child, C. M., 1907 a, Studies on the relation between amitosis and mitosis. 



(Biol. Bull., Vol. XII, p. 89—114. 1907 b, ibid., Vol. XII, p. 175—224. 



1907 c, ibid., Vol. XIII, p. 138—160. 1907 d, ibid., Vol. XIII, p. 165 — 184.) 

 Drzewecki, W., 1904, Über vegetative Vorgänge im Kern und Plasma der 



Gregarinen des Regenwurmhodens. (Arch. f. Protistenk., Bd. III, p. 107 



bis 125.) 

 Janicki, C. von, 1907, Über die Embryonalentwicklung von Taenia serrata, 



Goeze. (Zeitschr. f. w. Zool., Bd. LXXXVII, p. 685—724.) 



r ) The number of nuclei studied is much greater than this. 



2 ) A recent count of 3328 cells from 536 embryos of Taenia serrata gives a 

 total of 23 probable and 29 uncertain cases of mitosis. These were not distributed 

 uniformly thru the series, some slides showing no mitoses, while in others several 

 occurred. In general the older embryos showed more numerous mitoses than the 

 younger ones. This rule is not absolute, however. 



