SPERMIOGENESIS OF HELIX ARBUSTORUM. 
317 
Platner (91, 92) was the first to endeavour to distinguish the 
spermatogonia and spermatocytes, but his efforts were not followed by 
sufficient success. He hold the resting spermatocytes as spermatogonia 
[cf. his Fig: 11., PL XXIII. (91)], and could distinguish only one divi¬ 
sion in the development of the germ-cells, though he — as is seen 
from one of his papers (92) — observed all the chief stages in the 
division of the spermatogonia and spermatocytes, and only his sériation 
is incorrect. He found (93) the normal number of the chromosomes of 
Helix pomcitia to be 24. 
Zimmermann (131) distinguished in germ-cells two generations. The 
cells of the first generation — according to him — have a very small 
amount of cytoplasm, their chromatin forms loops which occupy the 
side of the nucleus directed toward the nebenkern, while the opposite 
part of the nucleus remains quite clear. The cells of the second gene¬ 
ration are much larger, and have a larger amount of cytoplasm. The 
chromatin of the resting nucleus forms spherical masses, in which also 
the constituent parts are to be distinguished. The number of these 
masses is at most 24. 
From Zimmermann 1 s statements it can be seen that he knew only 
one cell generation, i. e. the primary spermatocytes. The generation 
described by him as the first generation of the germ-cells is identical 
with the younger generation of the spermatocytes from the period 
succeeding the synapsis, and his second generation identical with the 
older spermatocytes. 
The results of Bolles Lee’s (10) valuable investigations have 
already been mentioned when discussing the spermatogonia. I empha¬ 
sized there that he could not distinguish the spermatogonia and sperma¬ 
tocytes from each other, and he regarded the young spermatocytes as 
spermatogonia, therefore he described these phases which we have had 
the opportunity of knowing as those of the primary spermatocytes, as 
belonging to the division of the spermatogonia. His results agree in this 
respect with those of Zimmermann. Bolles Lee regarded as resting 
spermatocytes the cells figured on our Fig. 5., PI. VIII. [cf. Bolles 
Lee (10), Pl. II., Fig. 30]. We have seen above that such cells are not 
resting spermatocytes, but auxocytes from the period after the synapsis. 
The chromatin of these cells — according to Bolles Lee — transforms 
itself into 24 spherical or ovoidal chromosomes. 
Ancel’s (2) results agree in general with those of Bolles Lee. 
He also regarded the young spermatocytes as spermatogonia, but he 
determined the series of the stages differently from Bolles Lee. Accor¬ 
ding to Ancel in the young spermatocytes first appear very fine threads 
