METHOD OF CELL DIVISION IN MONIEZIA. 145 



In certain favorable material I can see a central dark granule 

 about which appears a clear brownish court (iron haematoxylin 

 material) and outside of this the yolk granules develop (Figs. 

 31 and 32). Whether this is general I am unable to decide; 

 probably, it is. Child thinks, and it seems a logical conclusion, 

 that the bouquet stage is responsible in some way for the yolk 

 production. Similar conditions have been described by Janicki 

 for Tcsnia serrata, and by several authors, particularly Gold- 

 schmidt, for trematodes. Goldschmidt 1 thinks that during the 

 spireme stage a separation of somatic and germinal substance 

 occurs and that the "trophochromatin" escapes from the nucleus 

 to reappear later in the cytoplasm as yolk nuclei. Somewhat 

 analogous accounts have been given for the eggs of animals of 

 other groups. 2 



The yolk of Moniezia differs from that of Tcenia in that in 

 the former it occurs as spherules filling the entire cytoplasm 

 while in the latter there is only a single mass (in the earlier stages 

 more) as large or larger than the nucleus lying in the cytoplasm. 



The Ovarian Egg. The end result of these processes is the 

 ovarian egg. It is irregular in shape due to crowding by sur- 

 rounding cells and neighboring eggs, and contains a large germinal 

 vesicle located asymmetrically. Filling the cytoplasm more or 

 less completely are yolk globules of various sizes. The nucleolus 

 is now comparatively small and is located near the periphery of 

 the nucleus. Chromatin is distributed throughout the nucleus 

 in the form of fine granules attached to a linin reticulum. I 

 cannot say that centrosomes and centrospheres occur but I have 

 seen some structures resembling them (Fig. 34). In this condi- 

 tion the egg is ready for passage through the oviduct where 

 fertilization occurs. The lumen of the oviduct where it enters 

 the ovary is much smaller than the diameter of the egg so that 

 pressure is exerted on the egg during its passage causing it to 

 change its shape. After reaching the uterus it regains its spher- 

 ical form. 



The Vitellarium. Early in the development of the anlage of 

 the female sex organs there is set aside a certain portion of the 



1 See Janicki, p. 695. 



2 Cf. Conklin on Crepidula, '02. 



