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Part III. — Sixteenth Annual Report 



and in a cluster immediately around them, are clear and unstained, 

 suggesting either shrinkage, or more probably fluid that does not stain. 

 These chromatic particles may be more or less rounded in form, or, usually, 

 somewhat angular or irregular, and their size varies considerably. The 

 larger measure about Q-OOlmm., but most of them are under 0,5/x ; those 

 around the germinal vesicle are small. They are coarser in the smaller 

 eggs. This condition of the cytoplasm is very well shown in the small 

 eggs in sections of an ovary containing nearly ripe eggs preserved in picro- 

 sulphuric acid, and stained with eosin, rubin, and orange. The germinal 

 vesicle shows the usual granular network, the nucleoli are flattened 

 against its wall and are stained dark indigo blue, and throughout the 

 cytoplasm, here shown finely reticular, are hundreds of rounded granules 

 of various sizes stained precisely like the nucleoli. 



For example, in an egg in this section, measuring 0*126mm. by 

 0*098ram., the germinal vesicle measuring 0'042mm. by 0*049mm., the 

 nucleoli were about a dozen in number, ranging from about 0*002 to 

 0'0035mm., and all flattened against the membrane. In the germinal 

 vesicle, distinctly visible in the rather achromatic network, was a coil of 

 minute chromatic granules, the coil being 0*0112mm. in breadth, and free 

 chromatic granules lay close to it. The whole of the finely reticulated 

 cytoplasm was charged with minute, conspicuous granules, stained very 

 dark like the nucleoli, and of various sizes, the largest measuring about 

 0 00 18mm. Lying close around the germinal vesicle, the section of whose 

 membrane was very distinct but very thin, there were many of the 

 granules of the larger sizes, sometimes in little clusters; but they were 

 not limited to this position. At the periphery of the cytoplasm at 

 one part, where the zona was not in contact with it, the stained granules 

 could be well seen sticking to the somewhat flocculent-looking ground 

 substance. 



I was also able to trace the formation of the yolk-nuclei in some of the 

 eggs. I have alres.dy said that these bodies are very common in sections 

 of young eggs of the angler towards the periphery, and at the stage re- 

 presented in Fig. 12, PI, II., when examined with high powers, they ap- 

 pear rather as condensations of the cytoplasmic substance, with an 

 indefinite, difi'use, woolly-looking margin. In some of the smaller eggs 

 above described, I found that they were composed of a nest of chromatic 

 granules, formed either near or far from the germinal vesicle indifferently, 

 and I found various stages, from an aggregation of distinct granules to 

 an irregular ball, in which indication of the components could only be 

 made out with a high magnification. The yolk-nuclei in these cases are 

 formed by the coalescence of chromatic particles. 



In sections of the ovary of a John Dory, fifteen inches long, 

 caught on 2 2d July, preserved in picro-sulphuric acid, and 

 stained with eosin, saffranin, and hsematoxylin, the same conditions 

 were observed : --Minute ova, with a single bright nucleolus and 

 scanty coarse network, sometimes stellate, and no cytoplasm; larger, 

 with a more abundant network, nucleoli and karyosomes, and the primi- 

 tive cytoplasm charged with chromatic particles ; and in those somewhat 

 larger, the presence of more prominent granular fibrils in the germinal 

 vesicle. But in the dory the nucleoli are relatively larger and more 

 numerous, and the primitive chromatic cytoplasm is pushed outwards by 

 the growth of more finely granular less stained cytoplasm around the 

 germinal vesicle, so that it forms a deeply-stained ring at the periphery 

 of the egg. It is in this that yolk formation begins. In sections of the 

 ripe ovaries of the herring (caught on 28th January, and preserved in 

 the same way), the smaller eggs showed the same condition as in the 

 dory. For example, an egg 0 07mm., with a germinal vesicle 0'042mm., 



