1899] DEVELOPMENT OF THE MICROSPORANGIUM 339 
ig. 12). The successive stages in the process of segmentation 
could be easily traced. The constrictions gradually become 
deeperand deeper, while at the same time the chromatin is with- 
trawn from the constricted regions. The resulting segments 
were always of the same length as the mature chromosomes 
appearing on the nuclear plate. Repeated examination of these 
stages failed to reveal a V-shaped bending back of the segments 
‘omesponding to that described by many investigators for 
lium. Moreover, the chromosomes do not have four lobes at 
the end, as would be more likely the case if they were formed 
by the folding-back process, but only two. It seems, therefore, 
that in Convallaria at least the chromosomes, although double 
nature and hence sometimes showing a longitudinal split, are 
always straight and formed simply by the transverse fission of 
the chromatin thread. 
The changes which the chromosomes pass through while on 
the nuclear plate are very difficult to make out, and conse- 
| Mently little that is definite can be said about them. The 
“gments seem to be straight or slightly curved and lie mostly 
4 radial manner on the plate (figs. rg, 79, 20). The earlier 
‘tages show a nearly cylindrical chromosome, but very soon this 
comes changed into the characteristic +-like structures which 
a very Commonly seen at this stage. These structures seem 
eg formed, as Belajeff'* and Strasburger' have shown, by a 
ada Splitting at each end of the cylinder, but in peepee 
Staal Planes, The inner forks are drawn apart by, the spindle 
ie the two outer ones separate in the plane pe oe 
aa €. In many cases a fissure may be seen ape 
j - Pex of one long arm directly through the mi 
os ne (fig. 20). oo 
“the i ‘ei V-shaped segments resulting Ons the separa i 
le ves of the + pass to the poles in the ordinary man 
WES. 14, 75, 22). The daughter segments proceed with the 
3 _ Kenntniss der Karyokinese bei den Pflanzen. Flora, Erganzungsb. 79 ' 434- 
ee 
*yokinetische Probleme. Pringsh. Jahrb. f. wiss. Bot. 28: 183. 1895. 
