106 BULLETIN OF THE 



On " teased " preparations Owsjannikow often finds the zona deprived 

 of its cellular covering, but ordinarily the detached cells are to be found 

 in the form of a continuous membrane, on which a conical projection is 

 to be seen. The form of the projection corresponds exactly to that of 

 the external micropyle ; it is hollow ; the cells at the entrance to the 

 micropyle have the form of a crown, and become smaller and smaller 

 toward the bottom of the crater. I am not sure that I fully understand 

 the figure (Taf. I. Fig. 6) which the author refers to in this connection, 

 but it appears to me to be a view of an egg from the animal pole ; the 

 granulosa cells of the crater, having been detached, are seen partly in 

 side view, but somewhat obliquely, as a conical structure, and the pore- 

 canals of the external zona of the crater are visible where the granulosa 

 cells have been lifted. In the middle of the figure is an optical section 

 of that portion of the zona which forms the internal projection, and in its 

 centre the micropylar canal. There is apparently a single layer of cells, 

 and this I take to be the granulosa. It is to be regretted that the 

 author has not furnished us with a strictly radial section through the 

 micropyle and the accompanying structures on a sufficiently large scale 

 to enable one to determine what becomes of the membrana propria of 

 the theca folliculi in the region of the micropyle. One would infer, from 

 the statement that this granulosa cone was hollow, that the theca must 

 follow the course of the crater ; but if it does, it must be different from 

 all other known cases. Not even in Perca does the membrana propria 

 suffer any deflection or infolding due to the participation of the gran- 

 ulosa cells in the formation of a micropylar structure. I have also been 

 considerably perplexed by Owsjannikow's Figure 5 (Taf. I.). At first I 

 took it to represent a strictly diametric section of the egg and its mem- 

 branes. With that understanding of it, I imagined that the large oval 

 body just above the micropyle might possibly represent a single micro- 

 pylar cell in some way loosened from its natural position ; but more 

 careful study leads me to believe that this is a figure representing in 

 part an optical section, in part a surface view, and that the oval struc- 

 ture presents an oblique view of the external entrance to the funnel- 

 shaped cavity of the crater, still lined with granulosa cells, while all the 

 rest of the figure represents a view of the egg as it would be seen in 

 optical section. Owsjannikow states that the inner micropyle can be 

 regarded as a somewhat enlarged canal of the zona, and claims that it 

 subserves the nutrition and growth of the egg ; for he has traced from 

 the inner end of the canal a row of granular bodies which were con- 

 tinued in the yolk as a fine thread, which at last disappeared. This row 



