CYTOPLASMIC INCLUSIONS OF THE GERM-CELLS. 601 
the cell ; the latter is, so to speak, hanging in the balance 
when it begins to differentiate. If the stimulus is not definite 
enough an intermediate might be formed, and later degene- 
rate, as many cells do. For the moment I can think of 
several possible sources of stimulation. Abundant and dif- 
ferentiating male cells in the lumen might send the balance 
towards femaleness. Absence of any cells in the lumen might 
stimulate towards maleness. As a matter of fact, here often 
enters a direct contradiction of the real facts. I have several 
cases where a lumen, quite or almost empty, is producing either 
male or female cells alone. It should be said, however, that 
in the latter case the lumen wall still had some few yolk 
cells. 
Finally, I believe that the nucleus of the indifferent cell 
may be stimulated by a variety of external agencies to tend 
towards one sex, and that the nucleus is the cell organ 
responsible for the differentiation of the plasmatic elements. 
I conclude that the plasmatic elements do not influence the 
nucleus in this matter. 
d. The Different Sperm Generations in the 
0 votestis. 
The ovotestis lumen is continually giving rise to new sperm 
cells. The conditions of nutriment alter so much that very 
few of these generations arise under the same stimuli. 
The number of times which the primary spermatogonium 
divides, and the number of times the secondary cells continue 
fission, depends on the nutrimental conditions of the lumen. 
I think that the reasons for variation of the generations are 
as follows : 
(1) Spermatogonial divisions of variable number, leading to 
a variation in Nebenkern and mitochondria. It is a fact that 
such variation does arise through differing numbers of 
divisions. 
(2) The conditions of nutriment profoundly affect the 
appearance of the plasmatic structures in spermatogonia or 
VOL. 62, PART 4. NEW SERIES. 41 
