Ou the generative Organs and Products of Tomopteris onisciformis E. 437 



in the neighbourhood in the fork , where generative tissue has been 

 already formed. The endothelial layer is very thin, Fig. lob en, but 

 the activities of its cells give rise on the side next the lumen of the 

 fork to new cells. The endothelial cells become elongated, and these 

 prolongations are gradually constricted or divided off from the mother 

 cells, thus forming a superficial layer of daughter-cells, Fig. 13 ov'. 

 Division takes place in the ilaughter-cells, and probably also new 

 proliferations arise in the endothelial cells, till the tissue from being 

 one, Fig. 13, becomes many-layered, Figs. 14, 15. The outer surface 

 becomes more or less rounded in outline. Like the testes, the ovarian 

 tissue increases by the multiplication of cells both towards the apex 

 of the fork, and towards the undivided part of the parapodium, till 

 the greater portion of the cavity of the fork is filled up. In the 

 ovarian tissue, the cells, like those of the testes, are at first similar to one 

 another, Fig. 13, and in mounts of the whole animal are indistinguish- 

 able from sperm cells. This is the case in younger females, but as 

 the tissue advances in development, the older cells of the ovary be- 

 come greatly enlarged, and the organ appears more or less lobulated 

 on the side away from the place where it is attached to the mother 

 endothelium. Fig. 10 — 12, 14, 15 o.^ov'. These lobules usually consist 

 of a rounded mass of cells. Fig. 12 ov\ often with a giant cell in 

 each. Till staining agents are applied the mass seems to be a large 

 sphere with a number of smaller spheres inside, such as Carpenter. 

 Ä: Claparède have drawn (tab. 7, fig. 13), but when suitably treated 

 so as to bring out the cell-walls, the whole mass is seen to be made 

 up of a series of polygonal cells. Fig. 12 ov\ each of which contains 

 a large nucleus, n, and smaller nucleolus. These nuclei give to unstained 

 specimens an appearance of true endogenous cell-formation, the large 

 nuclei looking like cells. The whole mass , however, has apparently 

 arisen from the division of a single ovarian cell, and may be paral- 

 leled with the "Kliiftungsprocess" of Leuckart & Pagenstecher. 



The ovary may therefore be composed of very small and large 

 rounded cells and masses of cells, and in ripe or nearly ripe intli- 

 viduals this is always the case. The size and shape of the organ 

 and of the masses of cells in the organ differ according to the age 

 of the individual. 



As in some other worms, the generative products separate from 

 the ovary. Fig. 10 ovw., sometime before they are ripe or capable of 

 fertilisation, Fig. 10 ov. ovm. The products so liberated are those 

 contained in what was apparently a lobule of the ovary and always 



