REPRODUCTIVE ELEMENTS IN MYXINE GLUTINOSA. 65 



micropyle, in the section passing actually through the pole, is 

 seen the germinal vesicle, which is large and spherical in shape, 

 and therefore circular in section. It is composed of a thin 

 membrane containing fibrils and granules, but no conspicuous 

 germinal spot. Its position and appearance are seen in the 

 figure. 



On January 29th of the present year I obtained specimens 

 of Myxine in which the development of the eggs had proceeded 

 so far that the growth of the polar threads produced an effect 

 on the external appearance of the follicle. At each end of the 

 follicle was a slight protuberance, which was considerably 

 larger at one end than the other. On the surface of the pro- 

 tuberance were minute rounded elevations, evidently due to 

 the presence of the threads beneath. One of these eggs con- 

 tained in its follicle is represented of the natural size in fig. 

 11. Its length is about 21 mm., breadth 7 mm. Fig. 12 

 shows a section through the pole of that end of the ovum dis- 

 tinguished by the larger protuberance. The protuberance is 

 seen to consist of the connective-tissue layer, the processes, 

 and the thickened follicular epithelium and vitelline membrane 

 in their neighbourhood. The thickness of the membrane close 

 to the base of one of the threads is "29 mm., of the follicular 

 epithelium at its thickest parts '30 mm. The connective-tissue 

 layer is thinner than at the stages already described, and is 

 especially reduced above the terminations of the polar pro- 

 cesses j at the point marked x this layer was only "02 mm. in 

 thickness ; at the pole y it was '5 mm. thick. The germinal 

 vesicle and germinal disc are not altered in structure. The 

 micropyle is somewhat narrower, and the cells present in it at 

 previous stages have disappeared almost completely, only a 

 little debris remaining. The micropyle seemed also in these 

 ova to be open internally, though of this point I am not abso- 

 lutely certain. If there is a membrane closing the inner end 

 it is an extremely thin one. The vitelline membrane and the 

 follicular epithelium are both much increased in thickness, as 

 will be evident from a comparison between figs. 12 and 4 ; the 

 latter is magnified fifty times, the former only thirty-five 



VOL. XXVII, PART 1. NEW SER. E 



