o74 The Spermatogenesis of Bufo Lentiginosus 
but as Wilson (60) has pointed out, the figures given by McGregor and 
Meves show that the ring and the mid-body coexist in the young sperm- 
atid. Hermann’s conclusion would seem, therefore, to be invalidated; 
but I can see no reason why the ring, if it is not derived from the centro- 
some, might not be formed from a part of the idiozome or, possibly, 
from a nebenkern. 
There is as great a difference of opinion among investigators regard- 
ing the origin of the acrosome as there is concerning the formation of 
the middle-piece. Flemming (16) derives the apical portion of the 
spermatozoon of Salamandra from the achromatic substance of the 
nucleus; but this result is contradicted by the later researches of Meves 
(37) who finds, as does also McGregor, that this structure is formed 
from the idiozome. Broman (6) who has studied the formation of the 
spermatozoon in Bufo igneus, also derives the acrosome from the idio- 
zome; but it is difficult to reconcile his description of the manner in 
which this formation takes place with that given by any other investiga- 
tor of amphibian spermatogenesis. According to Broman, the idiozome 
becomes fixed at some point on the nuclear periphery and later the 
nucleus rotates in such a way that the idiozome is brought to the future 
anterior end of the spermatozodn. Whether the centrosomes, which are 
carried along with the idiozome, take any part in the formation of the 
acrosome is not stated. 
Several investigators, among them Field (14), Niessing (42), and 
Platner (44), have maintained that the acrosome is formed from the 
spermatid centrosome; but such an origin of the acrosome has been 
denied by later workers on the same or on related forms, who have traced 
the centrosome into the middle-piece: Henking (19), Wilcox (59), 
and Paulmier (43), among others, have derived the acrosome in insects 
from a nebenkern; while Lenhossek (32) has described-it in the rat 
as arising within the idiozome suddenly, as if it were a spontaneous 
thickening of the substance of the sphere from which it is later entirely 
separated, the sphere itself subsequently undergoing disintegration. 
The young spermatids of Bufo contain in addition to the nucleus and 
the cytoplasm, a single centrosome surrounded by a clear vesicle, and a 
rounded, deeply staining body, the acroblast; there is no granular. attrac- 
tion-sphere in the cell, neither is there a nebenkern. As the acroblast 
is present in the cytoplasm of the primary spermatogonia and can 
readily be traced through all of the subsequent stages in the develop- 
ment of these cells, there is no possibility that it arises in the sperm- 
atid either from an idiozome, a mid-body, a centrosome, a nucleolus or 
a nebenkern. 
