Helen Dean King 377 
stages (Figs. 79, 80), it is found at the anterior end of the sperm-nucleus. 
In describing the origin of the acrosome, Henking states that the mito- 
some divides and that a portion of it becomes infected by an “ un- 
zweifelhaft chromatisches Punktchen ” so that the whole body stains like 
chromatin and then wanders to the anterior end of the spermatid to form 
the acrosome. Henking makes no mention in the text of his paper of the 
small bodies in the cytoplasm, and I am strongly inclined to think that 
his “ infected mitosome ” may prove to be an acroblast. 
In this connection observations made by Foot and Strobell (17) are of 
interest. These investigators state that in the spermatozodn of Allolo- 
bophora foetida there are three centrosome-like structures, one at the 
base of the spine, one at the anterior, one at the posterior end of the 
middle-piece. It is perhaps possible that here, too, the centrosome-like 
body at the apex of the spermatozoén is derived from an acroblast. 
In all of the cases in which a body similar to the acroblast in Bufo has 
- been described or figured, this structure has the same characteristics: 
it is round or oval and somewhat larger than a centrosome; it always 
appears homogeneous and stains very intensely; it is usually surrounded 
by a clear area. It hardly seems as if bodies of unlike nature would have 
the same characteristics in the spermatids of such varied forms as the 
insects, the amphibians, and’the mammals. Few of the investigators 
who have mentioned the presence of this body in the spermatids have 
traced it back to the spermatocytes; and none of them have followed its 
history in the spermatid. I feel confident that further research will 
show that in many, if not in all, of the cases mentioned above, the 
rounded, homogeneous body in the spermatids will be found to be of the 
same nature and significance as the acroblast in the spermatids of Bufo. 
As the formation of the acroblast in the primary spermatogonia is as 
yet obscure, any conjecture I may make as to the origin of this body 
will be purely tentative. Judging from its staining reactions the acro- 
blast is not extruded chromatin; and the behavior of this body lessens 
the probability that it is a nucleolus. I am strongly inclined to the 
opinion that the acroblast is a purely cytoplasmic product, formed pos- 
sibly, from a condensation of a portion of the attraction-sphere at an 
early period in the history of the primary spermatogonia. If such 
proves to be the case, then in the spermatozoén of Bufo the acrosome 
has practically the same origin as the acrosome in the spermatozoon 
of Salamandra, Amphiuma, and Bombinator. 
ee 
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