768 THOS. H. MONTGOMERY, JR. 
CELL AXES, CENTRIOLES, FLAGELLA 
Each spermatogonium is distinctly bipolar (figs. 1, 3), with 
one pole occupied by the nucleus and the other by the mitosome 
and the greatest mass of cytoplasm; the long axis of the cell 
passes through these two. 
During the earlier growth period the spermatocytes show 
corresponding poles, which may be named, in accord with my 
previous terminology (’00), the central and the distal poles; 
the nucleus lies nearest the former, and there was also the cen- 
triole in the early anaphase of the last spermatogonial division, 
while the greater mass of cytoplasm and the idiozome lie at the 
distal pole. This constant polarity persists from the stage of 
fig. 5 to that of fig. 58. The primary axis of the first spermato- 
cytes is then a line joining these two poles, and the axis of the 
first maturation spindle comes to lie at right angles to it, while 
that of the second maturation spindle coincides with it. 
The centrioles of the spermatogonia (fig. 4) are exceedingly 
minute, and I have not restudied them with any particular 
attention. They were rather fully described in my paper of 
1898, but with too low powers of magnification for exact demon- 
stration. ‘They could not be seen in the spermatocytes until the 
idiozome had disintegrated. During the earlier growth period 
it is probable they lie within the idiozome, judging by analogy 
with the phenomena in other animals and for reason of the fol- 
lowing facts. In figs. 46 and 47, illustrating the separation of the 
halves of the disappearing idiozome (id), the nucleus is pointed 
at the idiozome pole; and in fig. 50, which shows the remains of 
the idiozome far separated from each other, the nucleus exhibits 
two correspondent projections. Such nuclear projections in 
these cells indicate the presence of centrioles, even though these 
are invisible, for in later stages, when centrioles become visible, 
the nuclear projections are always directed towards them. There- 
fore it follows from the appearances just described, that the cen- 
trioles have moved from the central pole of the nucleus to occupy 
a place within the idiozome at the distal pole, and that the cen- 
trioles leave this position within the idiozome in the primary 
