398 BOTANICAL GAZETTE [NOVEMBER 
and are distinguishable during the short resting period. In the second division the 
chromosomes split longitudinally along the line indicated in the loose spirem stage 
of the first division. Consequently, it is the product of the first longitudinal 
division which becomes separated at the second division, and not the product of a 
second longitudinal splitting as believed by those who support the theory of a 
double longitudinal splitting. The first mitosis is a reduction division, the second 
an equal division (Aequationsteilung). Besides the figures of Galtonia, a series 
of diagrams makes the process easily understood. An examination of Tradescan- 
tia gave approximately the same results, but in this form the processes are not so 
easily observed. The much studied Lilium, though not a favorable form, will 
bear a similar interpretation. 
The greatest difficulty in the investigation and the most important part of the 
discussion concerns the synapsis stage. At this period the chromatin withdraws 
from the linin thread and collects around twelve centers (Gamocentren) correspond- 
ing to the twelve chromosomes. The chromatin granules form loose groups, then 
unite to form bodies in which the separate granules can hardly be distinguished. 
These bodies elongate, become constricted in the middle, the granules of the 
two halves begin to separate, and with the aid of the linin form a continuous 
thread. The entire thread then splits longitudinally. That the twelve bivalent 
segments of this thread correspond to the twelve bodies counted during synaps!s, 
and that the transverse division of each bivalent chromosome again separates 
halves of that body, cannot be doubted. The view that there are differentiated 
chromosomes in the synapsis stage is consequently incorrect. Rather, the chro- 
matin content of the chromosome is in the form of small granules collected about 
a middle point, the number of these middle points corresponding to the reduced 
number of chromosomes and to the number of chromosome pairs. Y 
actually see the granules form a body which becomes divided into halves. 
STRASBURGER conceives that the granules leave the linin thread that there sig 
be a freer interchange among them than would be possible in the case of mgr 
tiated chromosomes. He proposes the term gamosome for the individual chro 
matin granules, and zygosome for the body which they form. F ae each Zyg" 
some comes two chromosomes, in the formation of which the linin takes part. 
only a secondary significance. The diminution of chromatin du 
period of the nucleus is not regarded as evidence that the chro 
bearer of hereditary qualities. In synapsis the individuality 2 a 
and maternal chromatin is given up. They unite to form a single hs ge 
from which come two new chromosomes. These two chromosomes do no 
tain exclusively paternal or maternal gamosomes. This throws li 
differences in the offspring of a pair of parents and also upon the § ath 
monohybrids. In discussing the question whether each eign of the 
the hereditary qualities of the organism, some evidence is found in fa 
view that the chromosomes are not of equal value. . 
A fuller presentation of these views and their relation to current concef 
would be welcome.—CHar.es J. CHAMBERLAIN. 
