43R J- H. FULLARTON, 



coDsists of several cells. These cells may be almost a spherical mass, 

 Fig. 17, or they may be au oblong rounded mass of cells, Figs. 16 a, b, c. 

 Very often the whole mass simulates true segmentation. 



The generative masses, when set free, float and circulate in the 

 coelom, as has been already described. Almost all observers who 

 have dealt with Tomopteris are familiar with the products at this 

 stage and the circulation has also been noticed by them. 



Difficulties emerge when we attempt to trace the ripening process 

 of the generative products after they have been set free. F'rom the 

 restlessness of the living animal it is impossible to watch changes 

 or advances in development of the generative products, even should 

 these take place at sufficiently close intervals so as to be capable of 

 appreciation by the eye with the aid of microscopic appliances. One 

 must therefore draw conclusions from the generative cells seen in the 

 body-cavity, their size, shape, contents, and their relative behaviour 

 on the addition of fixing and staining agents. The materials are, the 

 most advanced cells still in the ovary but on the point of being 

 liberated, Fig. 12 ov\ the masses of cells floating in the body-cavity 

 similar in character to these, Fig. 10 ovm., single cells or ova of 

 varying size. Figs. 17 — 23, up to the ovum of largest size. Fig. 25, 

 and a series of other cells not unlike the ovum but with one to about 

 sixteen or even thirty-two cells. Fig 28 et seq., in union with it. The 

 characters, which have helped me, are the relative amounts of proto- 

 plasm and of deutoplasm in the cells as brought out chiefly after 

 staining has taken place, the size and shape of the cells, and the 

 presence or not of polar bodies. 



The contents of the body-cavity in my opinion assort themselves 

 into three classes, first those cells which are developing to result in 

 the ripe ovum or second class of cells, and third, the cells which 

 have followed on the fertilisation of the ova. 



The cells ripening towards an ovum exhibit what Leuckart & 

 Pagenstecher called a "Kliiftungsprocess". Before liberation from 

 the ovary, the masses of cells are mostly composed of protoplasm, 

 and it is rare to find deutoplasmic sjjherules in them. Figs. 10, 11 

 and 12 show these masses in situ, and they are represented separa- 

 tely in Figs. 16a, 16 b and 16 c. 'J'he individual cells composing the 

 mass seldom project beyond the outline of the others, and in many 

 cases the whole mass approaches a spherical shape. But soon after 

 liberation from the ovary, the cells of the mass, F'ig. 18 et seq. 

 l)roject, and there is no longer any doubt that we have an aggre- 



