DAVIS: SPERMATOGENESIS. 83 
more marked than at any other time.. Figure 33 shows a spireme as 
seen from the pole. It is evident that the loops all tend to converge 
at a single point, where they are attached to the nuclear membrane. 
In reality, the ends of all the loops do not come together at a com- 
mon point, but some unite with each other a short distance from the 
point of attachment, so that the threads often appear to branch. It is 
almost impossible to make out the exact arrangement of the threads 
near the point of attachment, since they are so closely crowded to- 
gether (often overlying one another), and also since in this region the 
chromatin granules are usually much larger, and distributed along 
the linin thread at much longer intervals than elsewhere. In such 
cases it is often very difficult to follow the lightly staining linin thread. 
The next stage (/) marks the end of the growth period (Plate 3, 
Fig. 46). The spermatocytes have now reached their greatest size, 
both as regards the nucleus and the cytoplasm, while the chromatin 
has become more diffuse than at any other stage. Judging from the 
number of cells found in this condition, this is the longest of the 
spermatocyte stages. 
The transition from stage e to stage fis gradual and consists chiefly 
of an opening out of the loops, so that most of them come to lie close 
under the nuclear membrane. ‘The result is that in most cases the 
polarity of the spireme seems to have been lost and the whole appear- 
ance suggests that there is a continuous spireme extending around the 
periphery of the nucleus. Farmer and Moore (:05) have, indeed, held 
that such is the case in Periplaneta, but in the Orthoptera which I 
have examined I do not believe there is a continuous spireme at any 
time. In fact, during stage f, when in most cases there appears to be 
no trace of the former polarity, the loops for a considerable time at 
least retain their original attachment to the nuclear membrane. In 
nuclei which are favorably oriented so as to afford a view of the distal 
pole, the ends of the loops can still be seen to be attached to the nuclear 
membrane as in the preceding stages, but owing to the tortuous course 
of the threads around the periphery of the nucleus, all trace of the 
radiate arrangement is lost except in the immediate vicinity of the 
distal pole. In some species of Acrididae, where the polarity is much 
more marked, it is plainly distinguishable even at this stage. 
Concurrently with the opening out of the spireme loops the longi- 
tudinal split becomes indistinct, and the thread seems to stain much 
less deeply. This appears to be due chiefly to the chromatin granules. 
becoming broken up into much finer particles, which are irregularly 
distributed along the linin thread. At the same time the amount of 
