10 HUMAN SPERMATOGENESIS: A STUDY OF INHERITANCE. 



Condition D. 5 cases. D probably dividing at the equator (for it is absent 

 at the poles) , d at one spindle pole. Half the secondary spermatocytes would 

 receive d and J^D ; in them d would divide but not y&D, and there would be formed 



5 spermatids with y&d, and 5 with J^d and J^D. The other secondary spermato- 

 cytes would receive only %D> which would not divide in them, consequently 5 

 spermatids would receive %D and 5 would receive none. 



Condition E. 3 cases. Both D and d dividing in the equator. Every secon- 

 dary spermatocyte would then receive J^D and %d, and these would not divide 

 again. It would then be a matter of chance how these allosomes became dis- 

 tributed to the spermatids. There might be : either 6 spermatids with J^D and 



6 with y%d ; or 6 spermatids with y%D and J/£d, and 6 spermatids with no allosomes. 



Summarizing from the above the inferred distribution of the allosomes to 

 the spermatids, but omitting condition E because it presents alternatives, we 

 would find: 



133 spermatids with y 2 D + Y 2 d = 42.09 per cent. 

 133 spermatids without J^Z) + Yid — 42.09 per cent. 



25 spermatids with y^D = 7.91 per cent. 



25 spermatids with Yid = 7.91 per cent. 



That is, 42.09 per cent, of the spermatids contain 2 allosomes, the same num- 

 ber contain no allosomes, and 15.82 per cent, contain 1 allosome. 



With respect to allosome content there would, accordingly, be four classes 

 of spermatozoa, and not simply the two classes distinguished by Guyer. 



Our study on the variations of the second maturation division confirms these 

 conclusions. From the arrangement of the allosomes in this mitosis, however, 

 we may conclude still a larger number of classes of spermatids or spermatozoa. 



In condition c, 1 case, a small chromosome, probably d, containing a split, 

 lay nearer one spindle pole. Should it pass undivided to that pole, that spermatid 

 would receive the whole of d. In condition f three small chromosomes were found 

 at one spindle pole, one of which may be J^D, each of the others at }4d; the 

 spermatid receiving these would then get J^Z) and all of d. 



To the four classes of spermatids or spermatozoa already described, there 

 are, accordingly, possibly two others to be added: spermatids containing the 

 whole of d, and spermatids containing this and also J^D. 



There are then in man certainly four classes of spermatozoa with regard to 

 their allosome content, and possibly five or six. Scarcely any of the spermatozoa 

 examined show abnormalities and no degenerating ones were found, therefore 

 there is no reason to believe that all but certain classes of sperm degenerate or 

 prove incapable of fertilization. We have seen that the mature sperm differs 

 merely in volume by graded variation. 



Guyer reasoned that spermatozoa with two allosomes on entering an egg would 

 give rise to females, and that those without allosomes on fertilizing eggs would 

 produce males; "in the light of these facts we should expect the somatic cells 



