112 BULLETIN OF THE 



passage of the spermatozoon. 1 I realize that this is a speculation on 

 very narrow foundations ; for even if it could be shown to result from 

 absorption, it might be the protoplasm of the ovum, not the granulosa 

 cell, which accomplished the work. There are, however, still more seri- 

 ous objections to this view, which, though not disproving it, render it 

 very doubtful. The fact that in general pore-canals and orifices in cu- 

 ticular secretions are the results, not of resorption, but of the previous 

 existence of protoplasmic projections, makes it probable, without positive 

 proof to the contrary, that the same would be true in this case. 



The serious, and indeed, as it seems to me, insurmountable objection 

 to considering the whole micropylar funnel as the result of absorption, is 

 the condition which it exhibits in Lepidosteus, where there is a very 

 gradual diminution in the thickness, not only of the zona, but also of 

 the villous layer. It is not probable that any process of absorption 

 could result in diminishing the thickness of both layers so evenly with- 

 out affecting their mutual relations, unless perchance it should be 

 imagined that the zona was absorbed through the agency of the yolk, 

 and the villous layer by means of the granulosa cells. But even that 

 assumption would not help the case very much, for it would still have 

 to be explained why the shorter villi retained all the parts of the longer 

 ones, and in nearly the same proportions. 



While, then, the conditions clearly preclude the possibility of looking 

 upon the micropylar apparatus in general as resulting from a process of 

 absorption, it by no means follows that the micropylar canal may not be 

 produced by such activity. 



The other purpose which it has occurred to me the micropylar cell 

 may subserve, is to facilitate the penetration of spermatozoa. Not pre- 

 cisely that a minute drop of slimy substance, resulting from the degen- 

 eration of this cell and covering the orifice of the narrow canal, would 

 offer less resistance than water, but that its presence might prevent the 

 occlusion of the orifice by the accidental introduction of impenetrable 

 substances without itself offering any serious obstacle to the free en- 

 trance of the fertilizing element. 



If one were to attempt a phylogenetic explanation of the micropylar 

 funnel and canal in bony fishes, he might reason somewhat as follows. 



1 In Cunningham's Figure 3, the cells of the granulosa plug which form the 

 layer nearest the yolk — four of them being cut in the section figured — are all 

 larger than the remaining cells of the plug, but I am unable to say that any one of 

 them is the largest of all. 





