314 TAKU KOMAI 
may be said with fair certainty, that the two kinds of cells under 
consideration have a common origin, and that no nutritive cells 
transform into spermatogonial cells. 
GROWTH PERIOD AND MATURATION ‘MITOSES 
The chromatin of the nucleus which has undergone the last 
spermatogonial mitosis diffuses so completely in the nuclear 
cavity that the entire nucleus stains almost uniformly grayish 
with iron-hematoxylin. Soon, however, leptotene threads make 
their appearance in it. They increase gradually in thickness 
and staining capacity, and develop into separate threads (figs. 
8 and 9). They are so numerous and overlie one another so 
intricately that a correct count seems hardly possible. But 
roughly one may say that they are forty-eight, the above- 
mentioned diploid number. At first, they are distributed 
throughout the entire nuclear cavity; soon, however, they mass 
together in the center of the latter, leaving a wide space in the 
marginal region (fig. 10). In spite of the position of the threads, 
this stage in Squilla represents the synizesis stage. According 
to Nichols (’02, ’09), the same appears to be the case with the 
corresponding stages of Oniscus, Hippa, Talorchestia; and Idotea. 
No nucleolus, however, is found in the present form, contrary 
to her observations on those forms. 
At the climax of the synizesis, the individual chromatin 
threads can hardly be made out; but somewhat prior to this 
there is a period in which the disposition of the threads may be 
fairly clearly detected. Here the arrangement of the threads in 
parallel pairs is very apparent; several pairs, each consisting of 
two threads of nearly equal length, appear in the nuclear cavity 
(figs. 1l and 12). Thus it seems to be clear that we have before 
us ‘parasynapsis’ instead of ‘telosynapsis.’ The same is also 
true of Cambarus and Cancer (Fasten, ’14, 718) and probably of 
Idotea, Hippa, and Homarus (Nichols, ’09). 
When synizesis is over and the nucleus enters into diakinesis, 
the chromatin threads, nearly twice as thick as those of the 
preceding stages, come into view. In material fixed with 
