oft%t Fishery Board for Scotlayid. 



101 



delicate, filmy-looking layer of protoplasm may be detected outside the 

 germinal vesicle. In the great majority of cases this is aggregated at one 

 side of the germinal vesicle, or rather at one end, for it is usually now 

 somewhat ovate. The network has still further increased in abundance, 

 the threads, however, are more slender and not so coarse-looking; there 

 are numerous minute karyosomes, and in some cases a few small nucleoli 

 can be seen at the periphery, in the position and with the appearance of 

 those which are always afterwards so conspicuous in the teleostean egg. 



But the most striking feature about the eggs is the presence in the 

 primitive cytoplasm of brightly-stained granules, presenting precisely the 

 same appearance as the nucleoli within the germinal vesicle. I was at 

 first puzzled by them ; an egg would appear a little larger than those of 

 which I have been speaking, with a number of what appeared to be 

 nucleoli lying free around it, the cytoplasm itself being scarcely visible. 

 I was able to trace this condition through whole series of eggs up to those 

 O'OSmm. in diameter, and to trace the presence of a multitude of stained 

 particles in eggs very much larger. For example, in an egg measuring 

 0*02 1mm. by 0*01 26mm. the cytoplasm was aggregated at one end in a 

 layer 0*006mm. thick, slightly stained, and chiefly with haematoxylin, 

 and it contained a large number — between thirty and forty in the section 

 — of bright red granules exactly similar in size and appearance to the 

 nucleoli. The germinal vesicle contained the network described, more 

 abundant than in the smaller eggs, far less so than in those of larger size, 

 with numerous minute karyosomes, and with seven or eight small nucleoli, 

 mostly aggregated at the end where the cytoplasm was. In another egg, 

 measuring O'OSmm. by 0*024mm., the cytoplasm was also chiefly collected 

 at one end, but formed a distinct layer all around the germinal vesicle, 

 which measured 0*0196mm. by 0'0168mm. : the small follicular cells were 

 becoming flattened against, and attached to, the periphery. The germinal 

 vesicle, compared with the cytoplasm and previous stages, was markedly 

 achromatic and clear ; the network had increased in abundance, and was 

 formed of fine granulated threads with minute karyosomes, and with a 

 few very small inconspicuous nucleoli at the periphery. The cytoplasm 

 was pretty deeply stained bluish purple ; and it contained a large number 

 of the brightly-stained red granules, now somewhat irregular in shape, and 

 uniformly distributed throughout it; there were also present two or three 

 intensely black points — oil droplets which had been blackened by the 

 osmic acid. In some eggs about this size, and in those a little larger, the 

 network within the germinal vesicle appeared to be diflerentiated into 

 two classes of threads, finely granular and rather coarser with thickenings ; 

 or it may be merely that the aggregation of chromatin granules on some 

 of the threads was greater than on others. 



In larger eggs, measuring about 0*09mm., with the germinal vesicle 

 about 0 •047mm., the network of granular threads has increased in amount, 

 and the nucleoli are more conspicuous than in the earlier stages. Towards 

 the centre of the vesicle there are more marked fibrils indistinctly seen to 

 be composed of stained granules as in the later stages described below, 

 and also minute free chromatic granules in the neighbourhood. The ap- 

 pearance of the cytoplasm is interesting. The chromatic granules present 

 in it are exceedingly numerous — several hundreds may be seen in a sec- 

 tion of such an egg. Around the germinal vesicle there is a layer of them, 

 and they also tend to be aggregated at the periphery of the cytoplasm, 

 but throughout the whole of it they exist in numerous pockets, clusters, 

 and strings. The intervening portions of cytoplasm are very finely granu- 

 lar and stained purplish, while the granules themselves are red, but not 

 the brilliant red of the earlier stages; the spaces between the granules, 



