176 BOTANICAL GAZETTE [SEPTEMBER 
such that there is a parallel approximation of certain parts of the 
spirem to form long loops; while other parts, especially those near the 
center of the nuclear cavity, become knotted and entangled. In the 
closely contracted and entangled parts of the spirem it is not possible 
to make out clearly and definitely the arrangement of the chromatin 
thread, but there is no doubt as to the true nature of the longer loops. 
Sometimes the loops show a tendency to radiate from the more con- 
tracted entanglement of the spirem. The arrangement of these 
loops is very rarely so regular as figured by FARMER for Lilium candi 
dum (I. c., fig.9). The parallel sides of the loops are usually twisted 
upon each other, and the bend of the loop is often, though not always, 
toward the periphery of the nucleus. It is during this contracted and 
entangled condition that the thread segments, either partly or com 
pletely into the chromosomes. After segmentation the chromo 
somes begin to contract and thicken more rapidly, and as a result 
they become more scattered in the nuclear cavity, so that the rela- 
tion of the two segments toward each other can be readily made out. 
It is in this and the spindle stage that the chromosomes have ese 
most frequently figured. Those which show the greatest regulanty 
give the impression that they have been formed by a long piece of the 
spirem folding over in the form of a loop and the parallel sides of 
the loop twisting upon each other. Others appear as two pale” 
rods, which may or may not be twisted upon each other; and in still 
others the two segments are variously oriented toward each other, a 
has been figured time and again, and in the greatest profusion, by the 
different observers. om 
When one considers the chromosomes in this stage and aw 
longitudinally split spirem of the early prophase, the most Fe. 
conclusion is this, namely, that the two parallel rods, 
ments of each chromosome, of whatever shape, represent 
and parallel parts of the longitudinally split spirem; th 
thus split merely contracted and shortened, so that the 
thick halves of each chromosome seemed to owe their t : 
: . . however, the 
contraction and shortening alone. As a matter of fact, ee 
longitudinal split of the thread in Podophyllum becomes obli 
during the formation of the loose and more regula : 
“scarcely a trace of the fission can be seen; and, as previol 
or the two seo : 
at the spire” | 
two rather 
hickness '° 
il mm, 90 nat 
r spire vf sated 
| 
