134 
L. Digby 
in the somatic prophase, each fine thread wliich severally connects onesplit 
side of a chromatic portion ^Yith that of the next is single, in the hetero- 
type prophase this thread is double, signifying that each side of the 
paired segments represents a portion of a whole imivalent chromosome. 
According to the telosynaptic view fission dividing the chromosomes 
into two longitudinal halves at the telophase of the last premeiotic divi- 
sion, reappears in the heterotype presynaptic prophase. On the other 
hand according to the parasynaptic view this fission is not visible in 
the presynaptic phases. Both sets of observers are in fairly dose agree- 
ment as to its subsequent reappearance. It is more or less obliterated 
during the postsynaptic phases and then reappears in the univalent 
Segments of the bivalent heterotype chromosomes, and after being 
strikingly visible during the heterotype anaphase and telophase, it finaUy 
takes effect and cleaves the daughter chromosomes on the homotype 
spindle.- 
The study of Crepis virens does not throw much light on these contro- 
versial questions. During the telophase of the last archesporial division, the 
chromosomes become completely mirecognisable, so far as separate identity 
is concerned, and the chromatic bodies of the resting stages appear ‘de 
novo’ by chromatic concentration. Eosenberg (46) holds that the paired 
chromatic bodies of the prophases represent the associations of homologous 
chromosomes. On the other hand evidence afforded by this mvestigation 
pohits strongly to the conclusion that these paired bodies are the result 
of fission and not of approximation. The chief reason for this view lies 
in the fact that the chromatic bodies increase in number as the prophase 
advances, and furthermore that all stages in the process of fission can be 
recognised. Chromatic bodies exhibiting a similar paired arrangement 
are to be seen both in the ‘resting’ nuclei of the archesporium, and in the 
resting tetrad nuclei. In both these cases the pairing is interpreted as an 
early fission preparatory for the next mitosis. Rosenberg (47), m his 
experinients in feeding Drosera, found similar cases of closely paired 
bodies. He was not able definitely to decide whether they were the result 
of fission or of association, but inclined to the view of association. If 
the interpretation that the paired bodies originate from fission be correct, 
then the original chromatic body, formed by the concentration of chro- 
matin, must represent a portion of a whole chromosome. In the alter- 
native series of presynaptic phases in which the chroniatin is more finely 
distributed as beads in a linin reticulum, a converse series of events 
ensues. Beaded threads, each of which is regarded as a longitudinal haK 
of a univalent segment resulting from the preceding telophasic fission. 
