310 Chromosomes in the Spermatogenesis of Anasa Tristis 
An actual identification of the spermatocyte bivalents with the sperma- 
togonial pairs would demand that the relative size of the eleven bivalents 
of a group should be as constant as the equality in size of two daughter 
bivalents and this we do not find. If we would avoid this difficulty by 
assuming paternal and maternal individual differences, then we should 
seldom find two daughter bivalents exactly like, but this equality of 
daughter bivalents is a conspicuous fact.” 
An inconsistency in the relative size of the largest cross-shaped 
bivalent is seen by comparing Photos. 5 and 6, Plate IJ. In Photo. 6, 
there is not a marked difference in the apparent amount of chromatin in 
the large cross-shaped chromosome, and the one (next in size) just below 
and to the right of it, but in Photo. 5, on the contrary, there is much 
more contrast in size between the largest chromosome and the eight 
tetrads surrounding it. Greater variations in the relative size of chro- 
mosomes are common, though we find no such inconsistency in the 
daughter halves of bivalents. We would interpret the halves of each 
bivalent as identical with the daughter chromosomes of the first 
division rather than with definite individual spermatogonial chro- 
mosomes. It seems to us that the precocious separation of daughter 
halves—as shown in the microchromosomes—does not necessitate in- 
terpreting them in accord with the theory of the conjugation of 
paternal and maternal chromosomes.” It is certainly very significant 
that we do not find unequal daughter bivalents, each daughter half 
invariably indicating as equal a division of chromatin as is repre- 
sented in the daughter chromosomes of any anaphase or telophase—and 
yet we constantly find a variation in the relative size of entire bivalents, 
such variations making size relations of a chromosome a most uncertain 
guide for identification, unless the difference in size is so extreme it 
allows for individual variation, as for example, the microchromosomes. 
Compare the lagging chromosomes of Photos. 29 and 39, Plate III, as an 
illustration of the variation in size that may be shown by the same chromo- 
some at the same stage of development. We have pointed out these two 
photographs for comparison because the chromosomes at the poles of the 
two cells do not show any such marked contrast in size as is demonstrated 
in the eccentric chromosomes. The difference in size of these two lagging 
“Tf we assume that this frequent variation in the relative size of bivalents 
is due to the technique then it should produce a like effect on daughter 
bivalents, and this we do not find. 
1 Tn some cases the microchromosomes of the early prophases are nearly in 
contact. See Photos. 13 and 23, Plate I. 
