154 
Digby.—Ou the Archesporial and 
followed by a further longitudinal splitting of each daughter chromosome into 
halves (threads) (Figs. 86 and 87). Consequently, as the longitudinal halves 
(threads) severally associate in pairs, they bring about the reorganization 
of the double number of chromosome segments (see Text-fig., Nos. 25-28). 
It has not been possible to find stages in the building up of the 
chromatic masses, so quickly do the longitudinal halves (threads) appear to 
reassociate upon their partial separation, but it is assumed that each of 
these masses is a filament, derived from the reassociation of the split halves 
(threads) of a daughter chromosome of the heterotype telophase. This view is 
confirmed by the fact that throughout the homotype prophases, the daughter 
univalent chromosomes, instead of being closely associated as in somatic 
prophases, are organized as more or less independent individuals, and they 
even take up their position as such on the equatorial plate. 
These chromatic masses are arranged round that portion of the peri- 
phery of the nucleus which is remote from the cell-plate, leaving a central 
clear space. Accordingly, they emphasize that particular area of the nuclear 
limiting membrane, whereas the boundary of the nucleus towards the cell- 
plate is undefined and gives access to cytoplasmic strands. Wilson Smith 
( 18 ) also remarks on the bunching together of the chromatin on the side of 
the cell remote from the greater mass of ‘ kinoplasm \ 
The nuclear membrane gradually disappears, the chromatic contents 
collect closely together (Fig. 90), and the further events are involved in 
some obscurity. Spindle fibres radiate into this mass, and the chromatic 
segments become more and more indeterminate (Fig. 91). The segments 
loosen out along the fibres, and the nucleus elongates at right angles to the 
cell-plate of the heterotype division (Fig. 92). The evolution of the spindle 
fibres proceeds (Fig. 93), and the chromosome-like segments are greatly 
elongated. They become almost completely divided by fission into longi- 
tudinal halves (Fig. 93) ; in fact, the daughter chromosomes take up their 
position as independent individuals on the equatorial plate (Fig. 94) instead 
of dividing in the ordinary manner only when arranged on the spindle. 
As the daughter chromosomes move away from one another and 
proceed towards the spindle poles (Fig. 95) fission once more immediately 
appears in them, often resulting in a separation of each of them into com- 
plete halves (threads). This is the fission prepared for by the alveolization 
of the daughter chromosomes in the heterotype anaphase. Arrived at the 
poles (Fig. 96) the tension slackens, and the chromosomes draw together in 
the figure of a rosette, as seen from a polar view. They thicken considerably 
and for a time appear homogeneous, fission being temporarily obliterated. 
As anaphase passes into telophase (Fig. 97) the chromosome^ separate from 
one another and fission once more reappears ; each chromosome divides 
into two halves (threads) which are at first homogeneous, but rapidly 
become beaded (Fig. 98). In Fig. 97 one chromosome, in advance of the 
