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SEASONAL CYCLE IN PERCH SPERMARY 695 
countered by Dodds as to why this period of migration and cessa- 
tion from division should be inaugurated and why it should 
come to an end is also met in the present study. The point 
will be discussed further in another part of this paper. ‘The be- 
havior of the migrating germ cells in the perch would suggest, 
however, that the capacity for migration had not been exhausted 
when the embryonic germ cells had reached the germ gland, but 
that under favorable circumstances they might again undertake 
locomotion after a.period in which their energy had been used 
in a static condition resulting in growth and cell division. 
The amoeboid cells have been observed along the lobule walls 
shortly before the spermatozoa are discharged in April and con- 
tinuously until the period of spermatogenesis, which begins 
about the first of September. 
2. Period of proliferation and growth 
This period extends from the time in which the migrating 
germ cells begin to collect at the periphery (early April) till 
they are transformed into spermatogonia (early August). 
The transformation which the migrating germ cells undergo 
when they reach the periphery of the testis has already been de- 
scribed above. Active growth starts as soon as the cells are 
lodged, and by early May a small proportion have become con- 
siderably enlarged (fig. 3, a and b). The clusters at the periph- 
ery at this stage contain less than a hundred cells. By early 
July the clusters have increased considerably (fig. 30, G.c.) and 
theré is a larger proportion of the larger cells (fig. 3, c). Pro- 
liferation is going on, but very slowly, and it is evident that the 
increase in the clusters is partly due to the arrival of new mi- 
grating cells. The only mitotic figures in which a definite 
chromosome count could be made are furnished by these larger 
cells (figs. 35, 36). Twenty-seven chromosomes could be counted 
distinctly. Nucleus and cytoplasm maintain their former volu- 
metric proportion during growth, and the plasmosome also in- 
creases in size. The darkly staining bodies which appear at the 
edge of the nucleus when the cell first becomes lodged disappear 
during growth. 
