SEASONAL CYCLE IN PERCH SPERMARY 699 
5. Synapsis and maturation divisions 
There is no growth period after the spermatogonia are formed. 
In figure 3 all cells have been drawn to the same scale and there 
is a decrease in size from the largest germ cell to the mature 
spermatozoon. In this respect the perch differs from the am- 
phibia, from the dipnoans where the primary spermatocytes are 
described as nearly three times as large as the spermatogonia, 
and from many other vertebrates where there is a considerable 
growth. A condition somewhat similar to that in the perch is 
found in some of the insects. 
Some entire cysts show nuclei in which the contents are dis- 
tributed as slender threads. In many of them the threads are 
equally distributed (fig. 26), in others there is a contraction | 
stage in which the threads have been drawn into a ‘bouquet’ 
at one pole (fig. 40, a), while in still other stages there is the last 
degree of contraction. Here about three-fourths of the nuclei 
is clear, while the remaining fourth contains the threads drawn 
together into a dense mass (fig. 40, 6). 
The small size of the spermatocytes and the tenacity with 
which the chromosomes adhere to each other make any detailed 
study of the maturation divisions impossible. Figure 41, a and 
c, represent a polar and an equatorial view of a primary sperma- 
tocyte division in a metaphase. Figyre 41, 6, is an anaphase of 
the same division. No data were collected which would point 
toward the presence of a sex chromosome. A large number of 
dividing spermatocytes were examined, especially in the meta- 
phase and the anaphase, but no lagging chromosomes were 
observed nor any chromosome proceeding toward the pole more 
rapidly than the general mass. 
6. Spermatids 
The period in which spermatids are present in any one cyst, 
like the duration of the spermatocytes in any one cyst, is very 
short. The entire period in which they may be found in the 
testis, however, lasts from early September to the middle of 
December. 
