of the Fishery Board for Scotland. 



103 



showed a very highly-stained peri-nuclear zone, a large number of very 

 prominent nucleoli attached to the membrane, and a network containing 

 fibrils with chromatic granules attached, and free granules, some as large 

 as the smallest of the nucleoli, lying near them. 



The same condition of the primitive peri-nuclear protoplasm has been 

 observed in the small eggs of the catfish, solenette, sole, plaice, Zeugop- 

 terus and Gadus luscus. 



In the eggs of the dory which have reached the size and condition of 

 the specimen shown in Fig. 10, Plate III., and in which yolk is formed, 

 the appearance of the germinal vesicle shows that the process of differ- 

 entiation has gone a stage further. The germinal vesicle of such an 

 egg, measuring 0*013mm. by 0'009mm., is shown in Fig. 14, and it 

 will be observed that the nucleoli are large, deeply stained, numerous, 

 and nearly all peripheral. Scattered throughout its whole substance, 

 which appears somewhat dense and finely granular, there are a 

 large number of free, spherical, brightly-stained granules. The largest 

 of these measured scarcely 0"002mm. (while the smallest " nucleoli " 

 measured 0'004mm.), and the great majority measured less than 

 0*0005 mm. These free granules resemble closely the chromatic granules 

 in the primitive peri-nuclear protoplasm of young eggs. 



The most striking feature, however, is the presence of quite distinct coils 

 or loops of chromatic, spherical, equal-sized granules, or chromosomes, 

 placed near the centre of the germinal vesicle. Whether, in the complete 

 form, it is arranged as a spireme or in scattered loops and chains, I cannot 

 say. The granules in appearance and staining are precisely similar to the 

 smaller free granules in the karyoplasm. The area occupied by the coil 

 is about O'OSmm. in diameter. The convexity of the loops is, as a rule, 

 towards the periphery. The longest chain that could be traced continu- 

 ously measured 0 •024mm.; it was composed of about 25 granules ; with 

 one or two slight interruptions, where it was possibly cut through, it 

 could be traced for a distance of about 0-07mm. The larger of the free 

 granules, with a few nucleoli, were chiefly aggregated in this area. The 

 chromosomes are not at all feathery, as Cunningham has described in 

 some forms, but distinctly moniliform. The karyoplasm in the neigh- 

 bourhood of the chromosomes is clearer than elsewhere. 



In somewhat smaller eggs (Fig. 9, Plate III.) the mass of the germinal 

 vesicle is made up of a reticulum of finely granular threads, but in vari- 

 ous parts throughout it more coarsely granular threads can be seen, and 

 here and there a chain of four or five larger granules exists. Free 

 stained granules are also dispersed throughout the karyoplasm, and some 

 minute nucleoli may be present towards the centre. 



In eggs about O'llmm. the same condition is shown; the moniliform 

 threads can only be distinguished from the granular (linin) threads by 

 somewhat greater size and conspicuousness, and they appear to be in the 

 form rather of a branching reticulum than in loops or coils. Free 

 granules are also present. In eggs still smaller the moniliform threads 

 cannot well be distinguished from the granular threads. 



What is the interpretation to be placed upon the phenomena I have 

 described ? It is, I think, clear that chromatic substance is manufactured 

 in large quantities in the germinal vesicle, and that it passes out into the 

 cytoplasm. In the young eggs of the angler the primitive single 

 nucleolus appears to liquefy and to become diffused along the threads of 

 the scanty network to form karyosomes ; many of these, as they increase 

 in size, become free nucleoli flattened against the vesicular membrane, 

 and a very great deal of chromatic substance passes out into the 



