698 CLARENCE L. TURNER 
Three stages of the transforming cells are shown in figure 37. 
In the first stage there is a contraction of the entire cell and prob- 
ably the extrusion of a clear fluid. At any rate the boundaries 
which marked the limits of the cell at its maximum size are 
maintained, and there is a space between this boundary and the 
contracted cell, giving the appearance of a cell suspended in a 
chamber of clear liquid. The fact that only the transforming 
cells present this appearance, while all the surrounding cells are 
normal, would preclude the possibility that the condition is an 
artif act. Both nuclei and cytoplasm become more densely 
staining as further contraction takes place and darkly staining 
spherules appear in the cytoplasm and in the nucleus. The re- 
duction in volume affects both the cytoplasm and the nucleus. 
If changes in volume of the cell, the appearance of spherules 
in both the cytoplasm and the nucleus and the acquisition of the 
capacity to take a denser stain may be considered criteria for 
metabolic activity, the cells have undergone a marked change 
in their metabolism. 
4 
4. Spermatogonia 
It is impossible to determine the exact number of generations 
through which the spermatogonia pass before spermatocytes are 
produced, but it is evident that there are at least five or six. 
As each spermatogonium gives rise to a group of descendants 
they form a cyst and all pass through the same stages of division 
at the same time (fig. 25). Consequently, it is possible to esti- 
mate the approximate number of descendants to which a single 
spermatogonium has given rise by counting the number con- 
tained in a cyst. 
In the dividing spermatogonium the chromosomes are so 
massed as to preclude a definite count. The most favorable 
cells were those prepared in smears, stained with iron haemo- 
toxylin and viewed from the pole. The number found in the 
dividing primordial germ cells, twenty-seven, would probably 
appear if the chromosomes could be separated so as to permit a 
count. Dividing spermatogonia are shown in figure 39. 
