238 MICHAEL F. GUYER. 



spermatocyte nuclei may be seen in process of growth or of 

 division in a common mass of cytoplasm which shows no indi- 

 cation of being divided into separate cells. The condition often 

 persists through the following division stages with the result 

 that from eight to twelve spermatid nuclei may be found in one 

 syncytial mass. More frequently, however, what appears to 

 be a fragmentation of the cytoplasm without the appearance of 

 definite walls, into clumps containing fewer nuclei occurs. 

 Looked at from the standpoint of the relative roles of nucleus 

 and cytoplasm in heredity, this establishment of specific nuclei 

 in a more general matrix of cytoplasm might be regarded per- 

 haps as indicating the more individual nature of the former 

 and more generalized constitution of the latter. On the other 

 hand, inasmuch as but little cytoplasm enters into the makeup 

 of the ultimate spermatozoon the condition may not be of as 

 much significance as one is at first thought tempted to attribute 

 to it. 



Notwithstanding the scarcity of intelligible prophase stages 

 in the primary spermatocytes, at metakinesis, there is to be 

 found in abundance a characteristic chromatic element of con- 

 stant shape and size which behaves like the typical X-element of 

 insects. Whatever the theoretical interpretation may be, the 

 presence of this element can be abundantly demonstrated. It 

 not infrequently comes to be at or near one pole of the spindle 

 while the ordinary bivalent chromosomes are still in the equa- 

 torial plate stage (photos 8-13; Figs. 134, 137, 145, 146, 149). 

 At a slightly earlier period it is nearer the equatorial plate- 

 commonly just above or below (Photos 15, 20, 22; Figs. 135, 

 138, 139, 159), but very frequently also at one edge (Figs. 148, 

 154-158). Unless preparations are very strongly destained it is 

 likely to escape detection in such positions as the last, since in 

 heavily stained preparations the whole chromatic figure becomes 

 a blurred mass. In fifteen cases I find I have recorded curved 

 elements at each pole of the same spindle, the presumption being 

 in such instances that the original special chromosome has 

 divided as do the ordinary bivalent ones of the spermatocyte. 



Boring and Pearl ('14) have published a paper on some phases 

 of the spermatogenesis of the domestic chicken. They find 



