SPERMATOGENES1S OF SCUTIGERA FORCEPS. 1/3 



of which extend far into the cells. The fibers are exceedingly 

 numerous, but not so heavy nor so darkly staining as when 

 attached to the chromosomes during the metaphase and directly 

 following it. Considering the size of the spindle, its disintegra- 

 tion occurs in a remarkably short time, indeed it begins as soon 

 as the chromosomes have reached the extremity of the spindle.. 

 Until this time, the fibers were extremely heavy and presented 

 a smooth appearance. But now they gradually become fainter 

 and more' granular, while those at the sides appear more and 

 more feeble, until they can scarcely be distinguished from the net- 

 work of the cytoplasm (Fig. 20). By the time they are pushed 

 in to form the sheaf-like bundle (Fig. 24), the separate threads 

 are of extreme fineness and delicacy. As the cell-wall presses 

 inward, drawing the spindle together, a row of darkly staining 

 bodies forms on the fibers in the equatorial plane, and appears to 

 fuse. Only those fibers on the periphery seem to be affected 

 thus, so that these granules do not form a plate, but a band 

 around the circumference of the spindle. The period between 

 the formation of the sheaf and the disappearance of the fibers 

 passes quickly, although there is a wide variation in the time at 

 which this takes place. In some cases the chromosomes are 

 still in the vesicular stage after the cells have separated and the 

 spindle fibers become greatly reduced in strength and 'numbers 

 (Fig. 22), whereas in other instances (Fig. 24), a complete re- 

 construction of the nucleus has taken place before invagination 

 of the cell-wall is completed. However, in no case does the 

 second division commence until the spindle has so completely 

 broken down that no trace of it remains. 



During this entire period, the centrosomes are not discernible, 

 but in the next metaphase they have reappeared, one granule on 

 the cell-wall at each pole, surrounded as in previous division by 

 a centrosphere and radiating fibers. These present an appear- 

 ance almost identical with those in the preceding mitotic figure 

 and bear about the same relative strength to the spindle fibers. 

 As the nuclear membrane breaks down previous to the second 

 mitotic division, the chromosomes all resume the same dumb- 

 bell shape as in the telophase of the former division. The acces- 

 sory chromosome again becomes lost among the others as they 



