INEQUALITIES IN HOMOLOGOUS CHROMOSOMES 119 
of each pair. In the first type of inequality which I described 
(figs. 4-8), all dividing cells examined showéd the members of the 
No. 4 pair unequal and constantly of the two respective sizes. 
The normal No. 4 chromosome was always of the size normal for 
No. 4 chromosomes and its deficient (No. 4) mate was likewise 
of a constant size but uniformly one-sixth less than the normal 
No. 4 in all cells, both somatic and germinal. The constancy 
of this relative inequality was very clearly shown, especially in 
those figures of the first spermatocyte division which appeared 
in lateral view (figs. 5-8). A similar uniformity of sizes I found 
in the unequal pair of the second type (figs. 12, 13) in both male 
and female animals. Abundant evidence of the relative sizes 
was given, especially in the tetiads of the first spermatocyte 
divisions. Every cell showed the No. 1 portion of the abnormal 
tetrad to be of the normal No. 1 size (figs. 10-13) and the longer 
i-valent portion to be likewise of a constant size. It was not 
only of uniform size in all the cells of the male individual, both 
somatic and germ cells, but in another individual, a female, it 
was also found to be of the same length (fig. 11). 
These facts indicate that in the latter case this abnormally 
long chromosome must have been handed on as such, not only 
through many generations of cell division, but also through many 
generations of individual animals. In the former case the defi- 
cient No. 4 chromosome—which was of practically the same size, 
not only in a large number of spermatocyte cells, the germ cells, 
but also in the body cells—indicates again that such an abnormal 
chromosome maintains its identity from generation to generation, 
from fertilized egg to fertilized egg. 
The permanency of these abnormal chromosomes has an im- 
portant bearing upon one problem of synapsis; upon the question 
as to whether or not a complete side-to-side fusion of homolo- 
gous chromosomes takes place during this period. I have at- 
tempted to illustrate my ideas by diagrams (figs. F, to F;, Gi to 
G,, and H, to H,). If we suppose that a fusion of the chromo- 
somes takes place, we should expect to find in the case of the 
unequal No. 4 pair something like figures F; to F; occurring. 
The shortened No. 4, pairing with that portion of the normal 
