METAPIIASE SPINDLE IN FOREICULA AUKICUliAlU A . 
259- 
are dealing is 7*1 /i ; and the ratio between this length and that 
observed at the corresponding stage of the primary spermato-^ 
cyte is 1*00 : 1*46. Now we do not know the ratio between 
the volumes of the secotidary spermatogonial and primary 
spermatocyte cells in the metaphase ; for a long period of 
growth intervenes. But, if the spindle length at the con- 
clusion of the spermatogonial metaphase is correlated with 
the cell volume, as we have reason for supposing that it is 
correlated in the two succeeding- mitoses, we can determine- 
the ratio between the volumes of the secondary spermato- 
gonial and spermatocyte cells at this stage. Let us assume 
this. Now, the ratio between the radii of two spheres of 
which the volume of one is equal to three times that of the 
other is 1*44 : 1*00, and this is almost identical with the ratia 
between the lengths of the spindle at the conclusion of the 
primary spermatocyte and spermatogonial metaphases ; for 
these lengths have been found to be 10‘4 and 7-1/^, and we- 
have already seen that — 
10-4 : 7-1 : : L46 : LOO 
The difference between these two ratios is so small that it 
may be ignored; and, if our assumption concerning the- 
relationship between the spindle length and cell volume in the 
metaphase is correct, Ave must realise that the volume of 
the primary spermatocyte cell at this stage is equal to three 
times that of the secondary spermatogonial. But the initial 
volume of the former must be half that of the latter, because 
the secondary spermatogonium divides to form two daughter 
primary spermatocytes. The volume of each primary sperma- 
tocyte must therefore be increased six-fold during the 
growth period. I have already shown by actual measure- 
ment that the volume of the chromatin is doubled during this 
period; and, since a large increase in the cell A^olume is 
always apparent at its conclusion, the possible connection 
between the length of the spindle and the volume of the cell 
in the spermatocyte metaphases may be extended to the- 
spermatogonial mitosis. 
