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JORDAX. [Vol. VIII. 



of the cytoplasm, such as shown in Fig. 7, precedes the for- 

 mation of the yolk itself. This is not a change due to reagents 

 for it is shown in eggs killed with Flemming's chrom-osmo- 

 acetic mixture and other reliable reagents, and moreover 

 appears only in eggs of a certain stage, younger eggs not 

 displaying this vacuolated appearance. A similar arrangement 

 of the protoplasm has been observed by Leydig ('88) in the 

 young eggs of Triton tacniatiis. The yolk is laid down upon 

 these trabeculas of the cytoplasm and in consequence of this 

 arrangement often has in sections a distinctly reticulated 

 appearance. Sometimes the yolk is formed first at one pole of 

 the &^g (Fig. 7) and then spreads to other parts, but I have 

 not been able to discover any constancy in this polarity, or 

 what relation such polarity bears to the pigmentation poles of 

 the adult tgg. More commonly the yolk appears nearly 

 simultaneously in different parts of the cytoplasm and forms a 

 more or less continuous ring. This ring of forming yolk is 

 considerably nearer to the periphery than to the germinal 

 vesicle, but never, at this earliest stage, lies in immediate 

 contact with the follicle cells. The yolk patches are early 

 distinguished by their great avidity for staining fluids, and by 

 their high index of refraction and coarse granulation in un- 

 stained eggs. I have been able to discover nothing that 

 would indicate that the yolk spherules increase by division ; 

 everything on the contrary indicates that they arise from points 

 of independent origin. With a high magnification (1000 diam- 

 eters) the beginning yolk patches show as in Fig. 5, PI. XV. 



I do not feel like speaking at all confidently as to the agencies 

 concerned in the production of yolk. I have frequently ob- 

 served appearances which may be interpreted as the stepping 

 out of very minute granules from the germinal vesicle into the 

 cell-body. These granules I have been unable to distinguish 

 on the one hand from numerous small stainable granules 

 (nucleoli }) inside the germinal vescicle or on the other from 

 the granules of the forming yolk. Whether it is safe to regard 

 this appearance as an actual migration of minute nucleoli which 

 in persona propria become yolk spherules seems to me doubt- 

 ful. There is, however, less objection to the view that certain 



