A critical study of the cytology of Crepis virens. 
115 
placed on the pairod chromatic bodies of the resting tetrad nuclei. It is 
evident that in the tetrad nuclei there can be no question of approxinia- 
tion of homologoiis chromosonies as only one set of chromosomes is present. 
No ineaning can be attached to the occurrence of paired chromatic bodies 
in the cytoplasni otving to their extra nuclear position. 
It is essential, when results are being considered, that precisely com- 
parable stages should be taken into accoimt. It has been shovm that, 
in the late telophases, the chromatic nuclear contents trend towards an 
ever increasing concentration, and consequently to a gradual decrease 
in the number of the chi’oniatic bodies, whilst, in the early prophases, 
division and fragmentation of the chromatic bodies once more increase 
their number. Viewed in the light of this interpretation, the paired ar- 
rangement of ‘prochromosomes’ figured by Rosenberg (46, Taf. 1, fig. 6) 
would be regarded merely as the relative position of two chromatic 
bodies, a position frequently met with in ‘resting’ nuclei (fig. 4.3), or 
at a slightly later stage, as the result of fission (figs. 49 and 51) of a 
single body. 
Presynapsis. 
Gradually the beaded sides of the chromatic bodies separate from 
one another (fig. 55), and the several beads he more or less independently 
in the linin which becomes definitely reticulate and tends to contract from 
the nuclear periphery (fig. 56). As the linin coUects round the nucleolus, 
carrying with it the roimded chromatic beads, some of the substance 
of the beads diffuses into it, giving it a coarser and more pronounced 
appearance (fig. 57). Contraction proceeds and the hnin may withdraw 
to one side of the nucleus (fig. 58). In cross section it appears to 
occupy the centre of the nucleus, and is attached to the nuclear limiting 
membrane by fine Strands (figs. 58, 59 and 60). As the association of the 
linin with the chromatic beads becomes more intimate, it takes an in- 
creasingly deeper stain. The beads begin to loose their identity, and tend 
to break up into smaller granulös and thcse are closely packed together 
in the linin substratum, forming a dose and granulär synaptic knot 
(fig. 61). 
It is a remarkable cii'cumstance that synapsis may also be achieved 
as the result of a series of presynaptic phases very different in character 
from those above described. In this alternative series, the chromatin 
occurs in smaller aggregations and is more evenly distributed through- 
out the nucleus. It is evident that Beer (3) ia his exammation of the 
early heterotype prophases of C. virens chanced to see only the finely 
8 * 
