CHROMOSOMES IN MAN 469 



The work of Duesberg, Guyer, Branca and Gutherz indicates 

 that the pre-meiotic number is about twenty-four, and that the 

 first spermatocyte metaphases contain one-half this number. 

 My studies show clearly that in a human embryo the somatic mitoses 

 display chromosomes in a number so much larger than this approxi- 

 mate pre-meiotic one, that the two numbers can not be the same. One 

 may not always be able to determine with exactness the number of 

 chromosomes, but when the number observed in a great many 

 eases is ten more than the expected average, the values in the 

 two cases must be different. 



It is a fact confirmed by countless observations that the number 

 of chromosomes characteristic of the spermatogonia and the ovo- 

 gonia, that is, the pre-meiotic number, is a constant one, and that 

 the same is true of the meiotic division figures. On the other 

 hand it is also known that the somatic mitoses do not always show 

 a number identical with the pre-meiotic one. That this distinc- 

 tion is not generally recognized is evidenced by the frequency with 

 which 'somatic' and ' spermatogonial' are used interchangeably, 

 although in the classic Ascaris embryo the somatic cells undergo 

 chromatin 'diminution' at the very beginning of cleavage. In 

 Ascaris the chromosomes in the somatic cells are larger in number 

 though smaller in size than in the germ cells. Krimmel ('10) 

 finds the opposite condition in regard to number in the embryonic 

 and somatic cells of the copepod, Diaptomus, in which the chromo- 

 some number varies between the reduced and the diploid value. 



While it appears that the somatic number in man, though not a 

 constant one perhaps, is different from the spermatogonial num- 

 ber, one should not overlook the results of Moore and Arnold who 

 observed sixteen bivalent chromosomes on the first spermatocyte 

 spindle. The diploid number, thirty-two, would be one closely 

 approaching the number found by me in the somatic cells. Their 

 single figure of three first spermatocytes in division does not show 

 sixteen bivalents in any case, nor does it support their claim in a 

 very convincing manner. 



The results of Winiwarther are so at variance with all others 

 that with the evidence at hand it is impossible to interpret them 

 properly. It may be significant that the spermatogonial number 



