ff 
108 L- Digby 
betweeu them (figs. 17 and 18). The beads niay retain their individuality 
or they may coalesce to form a chromatic Strand. When two such beaded 
or more or less homogeneous chromatic Strands approximate, a faintly 
staining medium blends the two together (figs. 18, 19 and 20). 
^leanwhile the nucleus has increased in size. 
The further stages of prophase are marked by a massing and con- 
centration of the paired chromatic strands (figs. 19 and 20) to fonn 
long bands, or thick aggregations. The various groupings of the nuclear 
Contents are nnited by fine Connections. All degrees in the approximation 
and condensation of the strands for the fomiation of the chromosomes 
are to be seen (fig. 20). 
This description of the evolution of the chromosomes in the somatic 
dimsions is closely in accord with that recently pubhshed by Beer (3). 
He has, moreover, found that an uneven concentration of chromatin may 
take place resulting in the production of a spiral spireme. This phenom- 
enon was described by Gregoire (19) in the roots of AUium etc. and he 
is shortly pnbhshing an account of the same in the nuclei of Crepis virens 
(21). In these preparations no such method of concentration has been 
observed; but when one considers the plastic character of the nucleus, 
and the endless variety of phases which it exhibits throughout the pro- 
gressive stages of chromosome evolution, it is not remarkable that the 
constmctive processes may develop on various lines. 
The fnrther concentration of the pahed chromatic strands results 
in the formation of large, thick, deeply staining chromatic segments, 
which as a mle show no trace of theh original double character. They 
ai'e many m number and nearly fül the nuclear cavity (fig. 21). Grad- 
ually these segments lengthen out, and curve (fig. 22) fonning a some- 
what wavy and not continuous spireme (fig. 22). Fission in parts of the 
spireme can now be seen (fig. 23). 
At this, and the previous stages, a nucleus appears to be preparing 
to evolve a far larger number of somatic chromosomes than the six 
characteiistic of this species. Couversely, in the anaphase of the hetero- 
type (PI. X. fig. 87) and homotype di^isions, the individual chromo- 
sonies tend to break up, transversely, into one or more portions. These 
facts point to a loose cojnbination of segments as fonning the real basis 
of each mature chromosome. Eosexberg (46) has figured a homotype 
anaphase (46, Taf. 1, fig. 27) with apparently four chromosomes, and 
puts forward the significant Suggestion that this ‘Querteilung’ may in- 
dicate that the chromosomes of C. i'ireyis are “eine Art Sammelchromo- 
somen” (p. 72). This hypothesis is strengthened by the fact that within 
