772 THOS. H. MONTGOMERY, JR. 
at its junction with the tail (figs. 144, 146), which may sometime 
be recognized in the mature sperm. 
Without relation to either centriole or axial thread is developed 
a cytoplasmic process or pseudopodium at the distal pole of the 
spermatid (figs. 114-116; 117-124). A similar structure does not 
seem vod have been described for any other flagellate sperm. I 
was unable to see it in fixed material, but in living cells it is most 
apparent, and indeed both it and the axial thread were added to 
my drawings from the study of living material. This pseudo- 
podium has some resemblance to that of a Heliozoan, beating 
slowly back and forth in the medium, bending and straightening. 
It is considerably thicker, especially at the base, than the axial 
thread. I could not find it in either living or fixed material 
later than the stage of fig. 124, so that 1t would seem to be a tem- 
porary organ of locomotion which may be of service in grouping 
the immature sperm into bundles. 
CYTOPLASMIC STRUCTURES 
A. Mitosome and cell plate 
All the spermatogonia possess at the distal end a body that is 
probably a derivative of connective spindle fibers of a previous 
mitosis, and therefore is probably a true mitosome; I have not 
studied its genesis, but have judged rather by analogy with other 
species. This is lettered mit. in figs. 1 and 3. It is denser than 
the rest of the cytoplasm, finely granular, and the mitosomes of 
contiguous cells are frequently fused so that ‘cell couples’ result. 
It is most evident during the rest stage but persists into the suc- 
ceeding prophases of mitosis. No mitosomes were seen in sper- 
matocytes or spermatids. 
Equatorial cell plates appear to be formed after each spermato- 
gonial mitosis (fig. 4), as well as after the first (fig. 100) and second 
(figs. 111, 112) maturation divisions. These are granule plates 
developed at the point of final separation of two daughter cells. 
They are of relatively short duration. 
