CHROMOSOME NUMBER AND PAIRS IN AMBYSTOMA 213 
As Meves states (p. 276), the differences in length between the 
spermatogonial chromosomes are too small, and the possible 
errors too great to affirm that these chromosomes are present in 
pairs of equal length. On the other hand, it should be added 
that these conditions offer no evidence against this claim. 
Furthermore, he shows a practically constant difference in 
length of 6 half-millimeters between chromosomes 8 and 9 in 
his table of measurements. An examination of these figures 
shows unmistakable evidence that there is foreshortening in chro¬ 
mosome 9 in three of these cells, and a probability that chromo¬ 
some 8 is much less, if any, foreshortened than chromosome 9. 
There results, therefore, in all of these cells a relatively uniform 
distribution of the chromosomes into two constant groups, a 
point which supports the claim that the relative lengths of these 
chromosomes remain constant. 
Concerning the somatic measurements, Meves concludes (p. 
282) “Die Fragen, ob bei gewohnlichen Gewebszellen des Sala- 
mandra Chromosomenpaaren unterschieden werden konnen, ist 
bereits von C. Rabl (’06, S. 72) verneint worden, ich muss mich 
ihm auf Grund der mitgeteilten Zahlen anschliessen” and “Die 
erhebliche Langendifferenz zwischen chromosomen VIII und 
IX, welche wir bei den Spermatogonien festgestellt haben, 
besteht bei den gezeichneten somatische Zellen nur in der Halfte 
der Falle.” This means, of course, that he believes that the 
chromosomes are not distributed into two constant groups in 
each cell and that therefore the evidence of the constant organi¬ 
zation of the chromatin is lacking in this respect. 
As already stated, the possibilities of error are so great that 
nothing is conclusively affirmed or denied by his measurements. 
However, an examination of the drawings of the chromosomes in 
his figures indicates certain probabilities. 
1. In three of the four cells (his figs. 15 to 17) in which the 
marked difference between chromosome 8 and 9 is not present, 
chromosome 9 is conspicuously foreshortened, and is in reality 
longer than his measurements indicate. Furthermore, chromo¬ 
some 8 in these cells may or may not be foreshortened, at any 
rate it is probably much less foreshortened than chromosome 9. 
