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CHARLES L. PARMENTER 
McClung (’05, ’07, and ’17), and others. But it is very im¬ 
portant to note that these irregular chromosomes arise and 
perpetuate themselves in a manner entirely consistent with a 
definitely organized chromatin and furnishes no support what¬ 
ever for Della Valle’s contention that the chromosomes are 
comparable to crystallizations of a salt solution and that their 
number in any cell is dependent upon the law of chance. 
C. Variations in other Urodeles 
Snook and Long (’14) find in the spermatogonial cells of 
Aneides lugubris nine containing clearly the usual number of 
twenty-eight chromosomes, and one cell with twenty-three. 
There are no other authentic reports of variable chromosome 
number in individuals of the Urodeles. The counts of Kolliker 
(’89), Fick (’93), and Jenkinson (’04) in the cleavage stages of 
Axolotl (Ambystoma tigrinum) were made for other purposes, 
and were not presented as accurate number determinations. 
Likewise, the counts of about eighteen to twenty-four, Champi 
(’13, p. 124) in several other Salamanders are only approximate. 
D. Variations in other forms 
Since a somewhat extensive tabulation of comparative germi¬ 
nal and somatic counts has been made and discussed by Hoy 
(’16), Harvey (’16), and briefly reviewed by Hance (’17 b), a 
repetition of this discussion is of little value. However, in the 
review of reported cases of variation a few general considerations 
have impressed me as worthy of mention. These may seem 
commonplace, but are evidently not altogether realized by some 
who are none too critical in their discussion of the significance 
of these enumerations. 1) As Montgomery (’01) long ago sug¬ 
gested, it is important to distinguish between variation in the 
chromosomes in the germinal line and those of differentiating 
somatic cells. In the germ cells I believe it can be stated safely 
that there are no certainly demonstrated variations in number 
which do not conform to a definite organization of chromatin. 
From time to time cases of apparent variation have appeared 
