spermatogenesis of the Mongoose, etc, 177 



merit of maleness; or more accurately, and in keeping with a quantitative 

 interpretation of sex in a final analysis, the accessory with its egg-homologue 

 (two X-elements) inhibits male-sex development, the single egg-homologue 

 in males being insufficient to counteract the male tendency, thus giving 

 origin to male individuals. In those instances where the female can be 

 shown to be the heterozygote, one X-element, according to the hypothesis, 

 may be assumed to be able to counteract the male tendency. 



ADDENDUM. 



The opportunity recently presented itself for the study of very favorable 

 human material. I am indebted to Dr. H. T. Marshall, professor of 

 pathology at the University of Virginia, for the specimen, a thin slice of 

 testicle fixed in Zenker's fluid, and obtained at autopsy from a negro aged 

 38 years, who died as the result of drinking wood alcohol. The material 

 is in excellent state of preservation. It was stained for study with iron- 

 hematoxylin. Primary spermatocytes in early postsynaptic phases (text- 

 figs. I to 9) are especially abundant and clear. Mitoses, however, both in 

 spermatogonia and spermatocytes, are infrequent, and, though a sufficient 

 number can be found at metaphase in the latter cells to furnish a fairly 

 satisfactory opportunity for attempting chromosome counts, I can come 

 to no definite conclusion concerning the actual number. My specimens of 

 primary spermatocyte mitoses, however, compare very favorably with the 

 illustrations given by Guyer and by Gutherz, every one of which I can 

 practically duplicate. 



An impartial judge of the figures must admit, I believe, that certainty is 

 impossible at least within an error of two — and two makes all the difference 

 between the presence of an accessory as urged by Guyer and denied by 

 Gutherz. The inherent difficulty of an accurate count is indicated by the 

 fact that the diploid chromosome number of the male cells has been given as 

 22 (Guyer), 24 (Flemming, Duesberg, Branca, Gutherz), 16 (Bardeleben), 

 18 (Wilcox), 33 or 34 (Wieman), and 47 (Winiwarter). It is significant, 

 however, that Guyer, Gutherz, Duesberg, and Branca agree on 12 as the 

 haploid (reduced) number; but Guyer, in contrast to the others, regards 2 of 

 these as univalent accessories ; also Guyer, Gutherz, and Winiwarter agree 

 in claiming the presence of a heterochromosome; and Guyer and Winiwarter 

 both report a dimorphism of spermatozoa, the former giving the number of 

 chromosomes as 10 and 12, and the latter as 23 and 24. 



It seems clear that a heterochromosome of some valency is present; it is 

 equally clear that the true nature of this body can not yet be established on 

 the basis of numerical relationships; the count is still uncertain as regards 

 at least 2 chromosomes. Study of my material convinces me that the 

 reduced number is not less than 12, but perhaps several more. As regards 

 conclusions respecting the presence of an accessory chromosome drawn from 

 a study of side views of metaphase spindles, it may be pointed out that 

 Guyer's and Gutherz's figures are substantially alike; but Guyer interprets 



