SPERMATOGENESIS OF SCUTIGERA FORCEPS. I /I 



appear. Either they lose their staining capacity or, having no 

 surrounding rays to mark them, are indistinguishable from the 

 numerous particles, the remains of the nucleolar portion of the 

 karyosphere, massed at this point. The chromosomes, having 

 reached the end of the spindle-fibers at first appear to be attached 

 to them at their extremities (Fig. 19), but as the fibers at once 

 begin to undergo degeneration and to become considerably 

 shortened, the chromosomes soon lie free in the cytoplasm (Fig. 

 20). While attached to the fibers they lie massed together (Fig. 

 20), but afterwards they spread over a greater area (Fig. 21) and 

 the separate elements may be seen. Each daughter-cell contains 

 eighteen chromosomes, which are still dumb-bell shaped, but 

 slightly granular and less intensely staining than before. One 

 cell contains in addition the accessory chromosome (Fig. 21), 

 still homogeneous in consistency and staining black. This ele- 

 ment, on account of its resemblance to the other chromosomes 

 (during the metaphase) could not be distinguished from them, 

 but at this period may plainly be discerned as it retains the same 

 form and staining capacity possessed throughout the metaphase. 



During the period immediately following the reconstruction of 

 the nuclear membrane takes place. This process is the most re- 

 markable phenomenon in the spermatogenesis of Scntigcra, but 

 as it takes place much more slowly in the second mitosis, afford- 

 ing better occasion for the study of the separate steps, it will be 

 discussed in connection with that division. 



The period between the two divisions passes quickly, although 

 the chromosomes undergo great changes in appearance. During 

 the metaphase of the first division, as was stated above, they 

 assume a dumb-bell shape and appear homogeneous (Fig. 17). 

 Immediately after this division they again present the same form 

 and appearance, although reduced in size. As the telophase ap- 

 proaches, they become somewhat more granular, but retain the 

 same general outline. After the reconstruction of the nucleus 

 has taken place, however, the chromosomes gradually become 

 more and more granular until they lie spread through the nuclear 

 area as diffuse masses. Their identity is not lost, although they 

 retain no definite form. As the membrane again breaks down 

 preparatory to the second division, they gradually contract and 

 assume once more their dumb-bell shape. 



