A critical study of the cytology of Crepis virens. 
123 
(fig. 96j, tvliich gradually resolve themselves into smaller granules (fig. 97). 
As the nuclei enter rest, the beads once niore concentrate into larger 
chromatic aggregations (figs. 98 and 99). 
Resting tetrad nucleus. 
The passing of the telophase of the honiotype division into rest has 
been closcly followed in Order that the origin of the chromatic bodies 
present in the resting nncleus of the tetrad might be deterinined. Once 
more it has not been possible to trace any direct relationship between the 
chromatic bodies of the resting tetrad nucleus and the chromosomes of 
the preceding homotype telophase, for during late telophase the sub- 
stance of the chromosomes is more or less distributed as small beads. 
It can only be definitely ascertained, therefore, that in the retro- 
gressive stages leading to the resting tetrad, as in the interkinetal rest 
between the last archesporial division and the heterotype prophase, the 
chromatic staining contents apparently decrease, and those that remain 
collect into a few deeply staining chromatic bodies, the ‘prochromosomes’ 
of Kosenberg. Rosenberg (46) has figured (Taf. 1, fig. 30) a resting 
tetrad nucleus with thrce ‘prochromosomes’. 
Whole nuclei have alone been taken into account for this investiga- 
tion. The number of chromatic bodies in a completely resting nucleus 
has again been found to be inconstant. It is always low, probably it does 
not exceed three, but it may often be less. In both the nuclei figured 
(figs. 100 and 101) two definite deeply staining chromatic bodies alone arc 
present. These bodies, as in the somatic and premeiotic resting nuclei, 
may show a duplex character (figs. 100 and 101) indicative of the future 
Separation of the daughter chromosomes. Rosenberg (46) has inter- 
preted this appearance in premeiotic resting nuclei as the association of 
homologous (diploid) chromosome segments, but this cxplanation cannot 
be applied to the precisely similar appearance eiicountered in the tetrad 
nuclei, in which only onc (haploid) set of chromosomes is present. Fraser 
and Snell (14) have emphasized this point in the gametophyte of Yicia 
faba. 
In a resting nucleus, apart from the chromatic bodies (figs. 99, 100 
and 101) smaU faintly staming beads are usually present. These beads 
may be arranged in pairs, and paired threads may join group to group. 
Their appearance suggests that they are portions of linin which have 
lost their chromatin, the latter having beconie concentrated into fewer 
but larger masses (figs. 100 and 101). 
