74 CYTOPLASMIC STRUCTURES IN THE SEMINAL EPITHELIUM OF THE OPOSSUM. 



marked by a sharp, black line. Although no such reticulum as Perroncito figures 

 for other mammals could be brought into evidence, I do not doubt that this darkly 

 impregnated substance corresponds to his apparatus of Golgi. That the method 

 was applied with full success is demonstrated by the presence of a beautifully 

 developed reticulum in the interstitial cells (fig. 34). Further, the Sertoli cells in 

 my preparations show a structure similar to that represented in Perroncito's figure 

 83. This pictures a Sertoli cell of the guinea-pig, containing a system of anasto- 

 mosed rods, which Perroncito considers a typical reticular apparatus. I can con- 

 firm this observation for the guinea-pig; in the opossum a similar condition is met 

 with, the difference being that the filaments are somewhat thicker and often 

 appear hollow. 



In the spermatocytes studied during the first phase of their evolution (fig. 27) 

 the apparatus has increased considerably in size and shows certain details in struc- 

 ture which may have been present in the spermatogonia, but which could not, 

 perhaps, be seen on account of the small dimensions of the body. Sections per- 

 pendicular to the apparatus show that the dark envelope is missing in the middle 

 part of the side toward the nucleus (fig. 27, left). Tangential sections (fig. 27, right) 

 reveal the fact that this dark envelope is not a solid shell, but is formed of a number 

 of filaments of varying thickness. Some of these filaments are anastomosed, yet the 

 impression given is never that of a typical reticulum, as Perroncito figures in other 

 species. Sometimes the apparatus is formed of two lobes reunited by a filament. 



During the second part of the growth period the change in the shape of the 

 apparatus apparently is in relation to the increased size of the spermatocyte; having 

 more space, the apparatus rounds out (fig. 28). During the prophase of the first 

 division, and as late as the metaphase (fig. 29), the apparatus appears as a sort of 

 unrolled coil located anywhere in the cytoplasm. In the anaphase (fig. 30) a num- 

 ber of granules, or clumps of granules, may be found scattered between the daughter- 

 nuclei, the thread having apparently fallen to pieces. The reconstitution of the 

 apparatus in the daughter-cells takes place gradually; there is a stage during which 

 two apparatuses are found in the second spermatocytes (fig. 31). Jordan, who 

 figures and describes a division of the "sphere" in what he considers as the first 

 prophase, must have mistaken the second generation for the first, as a fragmenta- 

 tion of the idiozome does not take place, as demonstrated in my description, before 

 the first metaphase. 



If we compare the behavior of the apparatus during mitosis in the testicle of 

 mammals with its behavior in invertebrates, as first described from silver prepara- 

 tions by Perroncito for Paludina, and much earlier by Platner for Helix for 

 literature see Duesberg (1914), pages 34-35 we find that in mammals the process 

 lacks the regularity exhibited in the lower forms. The apparatus behaves, as far 

 as I can judge from the accounts given, like the idioectosome of Stockard and 

 Papanicolaou. 



In the young spermatid the apparatus looks more like a reticulum than at any 

 other stage. Then a differentiation takes place; a vacuole appears which increases 



