280 Chromosomes in the Spermatogenesis of Anasa Tristis 
tions in the original observations and interpretations of the inyesti- 
gators who have studied this form, Paulmier, 99; Montgomery, o1; 
Wilson, 05-06. Paulmier observed twenty-two spermatogonial chromo- 
somes and this count was corroborated by Montgomery in 1901. Paul- 
mier further observed the persistence of the two small spermatogonial 
chromosomes in the resting spermatocyte, the subsequent unequal 
distribution of these two chromosomes producing the dimorphism of the 
spermatozoa. According to Paulmier, these small chromosomes form a 
bivalent which divides in the first spindle but fails to divide in the sec- 
ond—it passes undivided to one of the daughter cells. In 1901 Mont- 
gomery confirmed these observations.” | 
A contradiction of these observations and interpretations was pub- 
lished by Professor Wilson in 1905. First, he finds twenty-one not 
twenty-two spermatogonial chromosomes. Secdnd, the two small sper- 
matogonial chromosomes named by Wilson, the “ microchromosomes,” 
do not persist in the resting spermatocyte. Third, the univalent micro- 
chromosome of the second spindle divides and, therefore, does not cause 
the dimorphism of the spermatozoa. Although Wilson accepts Paul- 
mier’s and Montgomery’s conclusion as to the dimorphism of the sper- 
matozoa, this he claims is due to the unequal distribution of one of the 
larger chromosomes. ‘This chromosome he identifies as an odd sperma- 
togonial chromosome, finding only twenty-one chromosomes in the 
spermatogonia. He observes the persistence of this odd chromosome 
during the rest stage of the spermatocytes, sees it divide in the first 
spindle, but in the second spindle pass undivided to one of the daughter 
cells. In a later work Montgomery, 06, withdraws his earlier indorse- 
ment of Paulmier’s observations and unqualifiedly confirms Wilson in 
the important points in which Wilson differs from Paulmier, viz., the 
odd number of spermatogonial chromosomes (twenty-one instead of 
twenty-two) and the identification of this odd chromosome as the one 
which in the second spindle passes undivided to one cell, causing dimor- 
phism of the resulting spermatids. Professor Wilson, 07, states that 
Paulmier, himself, admitted his error in the count of the spermatogonial 
chromosomes, though this does not necessarily imply an agreement with 
Professor Wilson’s interpretation as to the significance of this odd 
chromosome. In any case, at present, these three investigators agree as 
to the odd number of spermatogonial chromosomes and the dimorphism 
of the spermatids and it is on these two points we take issue with them. 
2“T am able to confirm Paulmier’s account of the two naturation divi- 
sions,” p. 168. 
