﻿iqi6] MERR1 MAX— NUCLEAR DIVISION 319 



as to the reduction of chromosomes. This is probably, as Lillie (6) 

 suggests in regard to tetrad groups of Ascaris described by Brauer, 

 a purely physical phenomenon, a grouping due to precipitation of 

 oppositely charged colloidal masses. These groups in turn are 

 connected with each other by strings of less dense substance. A 

 side view of them gives the impression of short dark bodies sub- 

 tended by loops of lighter substance. They may present the same 

 pyramidal appearance as seen before the separation of the disks. 

 Pressure on the cover glass on turning the disks to full polar view 

 shows the disks to be of no appreciable depth, and to consist 

 approximately of 4 rows of tetrads (figs. 56, 57). As the disks 

 exhibit a tendency to be attracted to the poles they become cone- 

 shaped, the apex pointing in the long axis of the cell. 



A gradual pulling apart of the amalgamated material follows, 

 until, as in figs. 53-57, two opposing disks are seen. The position 

 of these disks, their shape, and consequent behavior in pulling 

 apart, show them to be but the fixed and stained masses which 

 constitute the jelly-like bands seen in living material evolving 

 from the turbid mass. The turbid mass corresponds to the fixed 

 spherical mass composed of irregularly disposed filaments or 

 granules. These disks of material as seen in fixed specimens are 

 not preceded by the splitting of chromosomes in prophase, as stated 

 by Mitzgevitsch (10), Berghs (i), and others. It is the amalga- 

 mated masses just as in S. crassa (8), the amalgamated spireme 

 that appears to be pulled apart, forming two opposing networks 

 in which no distinction of material now is apparent, unless it be 

 in the linin-like connections of the groups. 



With the formation of these networks, the space between the 

 two becomes very clear. All the granules making up the spindles 

 are absent, the intervening space between the networks being 

 crossed by a few strands (figs. 51, 52) which in later stages appear 

 to become attenuated and then disappear. These strands are 

 identical with the translucent cords which in living material con- 

 nect the separating jelly-like disks. Studies of living material 

 raise the question whether the matter in the disks may not move 

 more often to the poles in strands or streams not cohering in a disk, 

 but reassembling in the form of disks when the poles are reached. 



