62 CYTOPLASMIC STRUCTURES IN THE SEMINAL EPITHELIUM OF THE OPOSSUM. 



figs. 7, 15, and 17) as a very conspicuous body. As already stated, it can not be 

 seen in preparations after Benda (figs. 16 and 25), but appears very clearly in 

 smears stained with iron hematoxylin. The centriolar granules located in the 

 collar are represented by von Korff (text-figures 3 and 4) as three granules disposed 

 very much like the same granules in my figure 13. Retzius, however, describes, 

 instead of the two posterior granules: 



"einen kleinen dunklen Halbring welcher wohl auch zum Centralkorperapparat 

 gehort und dann als die vordere Abteilung des distalen Korpers zu betrachten ist." 



My observations agree with von Korff's, with this difference; that the two 

 posterior granules, which are still apparent in spermatozoa taken from the testicle 

 (fig. 16), appear usually more or less completely fused together in smears from the 

 epididymis (fig. 25). Slight differences in the shape and length of the head and 

 middle piece, noted between smears and sections, are probably due to a sort of 

 capillary action exerted in the former (cf. figs. 16 and 25). 



CHONDRIOSOMES. 



Since Jordan's surprising conclusions, a reinvestigation of the chondriosomes 

 in the testicle of the opossum has always appeared to me as necessary. An effort 

 made several years ago to collect material from the zoological gardens in Europe 

 proved unsuccessful, so that the present opportunity was gladly taken. 



The details of Jordan's description will be discussed when the necessity arises, 

 in connection with my own observations, and I shall limit myself to a resume of 

 his main conclusions. While he admits that chondriosomes are present in the 

 spermatids, and that part at least of these bodies form the spiral filament of the 

 spermatozoon, he denies their existence at certain stages of the process of sperma- 

 togenesis. Concerning their absence in the spermatogonia and in the Sertoli cells, 

 he does not express himself very definitely. He then continues : 



"But my preparations leave no doubt respecting the absence of mitochondria during 

 the early growth period of the primary spermatocytes. For this generation of cells, they 

 first appear during the later growth period and during a period coincident with a transi- 

 tory achromatic reticular phase of the nucleus. This observation is the more significant 

 in view of the fact that both within and without the nuclear wall are similar darker- staining 

 bodies. Subsequently such bodies (now deeply staining, sharply contoured spheres and 

 dumb-bells) are aligned on the nuclear membrane externally. All the evidence here hints to 

 a nuclear origin of mitochondria, i. e., they appear to be transformed chromidia (p. 59.)" 



Of this nuclear origin Jordan is not, however, altogether sure. The main 

 point upon which he insists is their discontinuity. 



"I believe that the fact of their apparent absence in the young spermatocytes of the 

 opossum (and possibly other forms) is one of the strongest arguments against the Benda- 

 Meves-Duesberg theory of their continuity and hereditary significance" (p. 69). 



There is no doubt that Jordan's conclusions, if verified, are of considerable 

 importance. I have from the beginning been aware of it, and have been anxiously 

 awaiting an opportunity to study the same material. At the same time I could not 



