CHROMOSOME NUMBER AND PAIRS IN AMBYSTOMA 201 
of the chromatic elements are directly comparable to the size 
and number of the fluid crystals which are formed in a solution 
under different conditions. 
These contentions he supports with the claim (’09) of a 
variation of nineteen to twenty-seven chromosomes in forty 
mitoses of the peritoneum, and (’ll) by a very large variation 
in the blood cells of Salamandra maculosa. These observations 
he supplements with a long list of citations of chromosome num¬ 
bers which he interprets as supporting his contention. 
But, following an apparently frank and critical discussion of 
the accuracy of his observations in the peritoneal cells, he says 
(’09, p. 116) that he is only sure of his enumeration in twenty- 
five of the forty cells discussed. These twenty-five complexes 
he describes as being very clear. The range of variation in these 
cells is as follows: 
Number of chromosomes.... 19 21 22 23 24 25 26 27 
Number of'mitoses. 1 1 1 6 16 12 2 1 total 40 
Number of mitoses. 1 1 3 10 8 2 total 25 
An examination of his descriptions and figures may indicate to 
some extent the reliability of these counts. 
His count of 22 chromosomes was made upon a polar view of 
a very late anaphase (fig. 2) in which he states the smaller chro¬ 
mosomes in the center of the complex were beginning to go to 
pieces and becoming indistinct, and his only doubt is whether 
the chromosome numbered 18 is one or two chromosomes. But, 
judging from similar stages in my material, it seems to me that 
where the chromosomes are beginning to go to pieces in as 
crowded a condition as this must be, such a complex is not a 
safe object for an exact chromosome count. 
Instances of this kind make it seem possible that conditions 
which he considers clear for an exact count might be much less 
conclusively clear to others, and that his drawings do not represent 
the actual conditions in his complexes. 
Since his citations of chromosome number variations found in 
the literature have been discussed by Montgomery (TO), Wilson 
(TO), and by McClung (T7, p. 548 ff.), it is not necessary to 
