306 
Dï L. SOÓS 
neous, because the nuclei of the spermatogonia and those of the base- 
cells lie originally in the same ground substance. The cytoplasm of the 
base-cells can be easily distinguished later, in which the spermatogonia 
cannot be imbedded in cpnsequence of its poverty. 
A part of the cytoplasm surrounding the nucleus later differen¬ 
tiates. The nuclei afterwards pass out of the common plasm, and seize 
the cytoplasm differentiated around them, thus originate cells having a 
typical constitution. 
The division of the spermatogonia is to be seen on Figs. 3—7., 
PI. VII. I remark by the way that in follicles in which the spermatozoa 
are abundantly developing, only few cells in division are to be found, 
from which we can conclude that their chief division period lies in a 
former stage of development. 
As the nucleus of a spermatogonium prepares for division, its 
chromatin resolves itself into a spireme, consisting of thin threads 
(PL VII., Fig. 3.). The threads shorten and thicken afterwards, and 
transform themselves into short and thick, arcuated chromosomes 
(PL VIL, Fig. 4.), which afterwards become still shorter, spherical or 
ovoidal (PL VIL, Figs. 5—6.), and then arrange themselves in the 
equatorial plate. We find then the number of the chromosomes approxi¬ 
mate to 48, which number is equal to that found by Angel in the 
«large germ-cells». The true number of chromosomes can be scarcely 
determined, because they are crowded in relatively small cells, but it is 
. certainly greater than 40. Former investigators (Platner, Bolles Lee, 
Prowazek) stated the number to be 24, and it was only shown by Ancel 
that the true number is 48, which agrees with the number found in 
the first blastomeres, therefore, it must be their normal number. Accor¬ 
ding to Ancel this normal number can be found only in the «large 
germ-cells» — the mother cells of the spermatogonia — which number 
in the first phases of division become reduced to 24, i. e., the reduc¬ 
tion takes place in the spermatogonia. The cromosomes of the 
spermatogonia of H. arbustorum , however, are certainly not 
reduced, therefore the reduction must take place in a later stage of 
development. It seems to me quite indubitable that even the number of 
the chromosomes of H. pomatia does not become reduced in the sper¬ 
matogonia, but the reduction of this species is like that of H. arbus¬ 
torum. My conclusion is based upon the fact that the mode of reduc¬ 
tion of H. arbustorum has — according to my observations — a gene¬ 
ral value in Pulmonates. Ancel’s error was due to the circumstance 
that he — as can be seen from his figures — could not precisely 
distinguish the spermatogonia from the first spermatocytes, and regarded 
