SPERMATOGENESIS OF SCUTIGERA FORCEPS. 1/5 



As was suggested above, this process occurs in both sperma- 

 tocyte divisions, but in the first, it takes place much more quickly 

 than in the second, and thus offers fewer examples for study. 

 In case of the first division (Fig. 22), these vesicles always lie 

 close against one another, whereas at the close of the second 

 division, they are often widely scattered through the cytoplasm 

 (Fig. 25). In the first division, too, the nucleus immediately 

 after fusing becomes spherical, and all traces of its vesicular condi- 

 tion are lost. But at the close of the second division, the nucleus, 

 in place of at once becoming spherical, retains for a considerable 

 period traces of its former condition (Fig. 28), and often loses 

 them only when transformation into the spermatozoon takes 

 place. The membrane surrounding the nucleus at first appears 

 very thin, like that of the vesicles ; but soon after fusion is com- 

 pleted, it seems to increase considerably in thickness, and resem- 

 bles that of the first prophase. 



The only case which I have found of an occurrence resembling 

 this was reported by Sutton, 'oo (Brac/iystola magna]. The 

 metaphase is passed without exhibiting any unusual phenonenon. 

 But during the telophase, an occurrence somewhat similar to 

 that found in Scntigcra takes place. " Each chromosome, on 

 reaching the pole, begins to disintegrate, and at the same time, 

 reconstructs its share of the nuclear membrane as a closed vesicle 

 about itself. Later, all these vesicles become intercommunicating 

 at their polar extremities, with the exception of one, which re- 

 mains absolutely independent throughout its entire existence. 

 The chromatin of the ordinary chromosome becomes diffused 

 evenly in the nuclear space, while that of the one in the separate 

 vesicle (the accessory chromosome) is deposited upon the inner 

 surface of its capsule." 



The spindle of the second mitotic division is markedly differ- 

 ent from that of the first, although in the metaphase the two bear 

 a distinct similarity. During the telophase, the breaking down 

 of the net-work of the cell in the equatorial region and the spread- 

 ing of the spindle fibers across this area is essentially the same 

 as in the previous division, except that the fibers here are con- 

 siderably fewer. As a result, no prominent sheaf-like bundle 

 is formed when the constricting of the wall occurs, but these 



