CYTOPLASMIC STRUCTURES IN THE SEMINAL EPITHELIUM OF THE OPOSSUM. 53 



number of other authors, he believes that the caudal tube eventually intervenes 

 in the constitution of the middle piece. Since in the guinea-pig, the degeneration 

 of the caudal tube is obvious, Oliver's description would lead one to believe that the 

 same structure can undergo a different fate in different mammals. I must say, 

 however, that I am not convinced. Oliver describes the process as follows: The 

 caudal tube breaks off the nucleus just before the centriolar ring begins to migrate, 

 then becomes increasingly narrower, surrounding more and more closely the axial 

 filament. At the same time "the cell membrane covering the caudal tube has fused 

 indistinguishably with the latter." The question which immediately suggests 

 itself to me, but which, if Oliver's description be correct, I am unable to answer, 

 is, where are the chondriosomes? These bodies are never, to my knowledge, found 

 within the caudal tube, nor can they be located between the caudal tube and the 

 cell boundaries, according to the quoted description. I would add also that the 

 separation of the caudal tube from the nucleus appears to me, from Oliver's draw- 

 ings, to be an accidental rather than a normal occurrence; and that between figure 

 32, in which the caudal tube is still far from being fused with the axial filament, 

 and the next figure there is an important, unfilled gap. 



Stockard and Papanicolaou have given a description of the fate of the idiozome 

 (they spell it idiosome, after Regaud's proposal, 1910) in the guinea-pig. The 

 present summary is made from their communication at the meeting of the Anatom- 

 ical Society (1916) and from the abstract published in the bibliographic cards issued 

 by the Wistar Institute (No. 155). The idiosome of the primary spermatocytes 

 consists of two spheres, one inclosed within the other. During the process of 

 division the outer sphere (idioectosome) breaks into irregular pieces, while the 

 inner one (idioendosome) forms a great number of granules (idiogranulomes). The 

 pieces of the idioectosome and the idiogranulomes flow together in each of the 

 secondary spermatocytes and form a new idiosome consisting of a spherical idioec- 

 tosome which contains a number of idiogranulomes. During the division of the 

 secondary spermatocytes the idioectosome breaks up again, and its pieces are dis- 

 persed in the protoplasm with the idiogranulomes. This process permits a uniform 

 distribution of the very important idiosomatic material during the division. In 

 the spermatids a new idiosome is reorganized, having a new idioectosomatic sphere 

 inclosing idiogranulomes, each granulome being surrounded by a small vacuole 

 (idiogranulotheca). The idiogranulomes and the idiogranulotheca flow together 

 to form a large spherical body (idiosphserosome) inclosed within a large vacuole 

 (idiosphaerotheca) . The idiosphserosome differentiates into an "upper" cap the 

 idiocalyptrosome, and a "lower" body the idiocryptosome; "the idiosphserosome 

 secreting as soon as formed on its surface, furthest from the nucleus, a new sub- 

 stance the idiocalyptrosome" (1916). The idioectosome (called also idiophthar- 

 tosome) is eliminated with the protoplasmic remains. The idiocryptosome and the 

 idiocalyptrosome persist in the spermatozoon as two caps, one beneath the other 

 and inclosed within the spermiocalyptra or idiocalyptrotheca, which is the trans- 

 formed idiosphserotheca. 



