A critical study of the cytology of Crepis virens. 
109 
the genus there is a somewhat wide ränge of chroinosome numbers, re- 
calling tliat of the family Ascaridae. Counts of the chromosonies of 
Crepis taraxacifolia have been made, and the numbers added to the ah'eady 
published list. The chromosonies of C. biennis are too numerous to 
deterniine accurately. 
Species 
Somatic Number 
Reduced Number 
of Chromosomes 
of Chromosomes 
C. virens 
6 
3. 
Rosexberg (46) 
C. tectorum 
8 
4. 
JUEL (24) 
C. taraxacifolia 
8 
4. 
Digby 
C. lanceolata var. flaiij- 
phyllum 
10 
5. 
Tahara and Ishi- 
C. japonica 
16 
8. 
KAWA (59) 
Tahara (57). 
Fraser and Sxell (14) have shovn that the chromosonies, in the 
somatic mitoses of Vicia faba, are frequently constricted into segments, 
and suggest that this phenonienon may explain “the often recorded Varia- 
tion in the chroinosome nimiber, and possibly also of the Mendelian phen- 
onienon of coupling” (p. 853). 
Gradually the lengths of spireme (PI. VIII. fig. 24) join together to 
form six twisted chromosonies (fig. 24). These are often orientated to- 
wards the nucleolns (fig. 25). The chromosonies contract and thicken and 
for a time the fission m their substance may be again lost to view (fig. 26). 
They then move aivay froiii the nucleolus; the nuclear cavity enlarges, 
and they appear to be propelled to the liniit öf, and sonietinies beyond, 
the nuclear boundary, before they are drawn in upon the spindle. 
Metaphase. 
The polar view of an equatorial plate (fig. 27) shows clearly the 
different sizes of the six chromosonies. In the words of Rosexberg (46) 
“von diesen 6 Chromosomen sind 2 entschieden größer, 2 kleiner und 2 
nehmen eine Mittelstellung ein” (p. 65). The daughter chromosomes 
may have separated froni one another before they go on to the spindle, 
or they may still be in contact. 
Anaphase. 
The chromosomes pass to the poles (fig. 29) and thus the cycle is 
completed (fig. 30). 
