8 BOTANICAL GAZETTE [JULY 
This is important in determining the character of the first divi- 
sion, as to whether it is to be a longitudinal or a transverse 
division of the chromosomes. 
Not only does the form of the ring aid in determining the 
position of. the chromosomes at the nuclear plate stage of the 
first division; the paired rods also serve to determine this. 
These lie parallel with the axis of the spindle. Even before the 
rings have moved to the nuclear plate there is a great tendency 
for them to separate into longitudinal halves. This occurs also 
at the nuclear plate stage. The tetrads separate more readily 
along the line of longitudinal division’ than they do on the line 
of transverse division. For this’ reason, at the nuclear plate 
stage, the figures with paired rods, rings partly or completely 
separated along the. line of the lengthwise cleavage of the 
spirem, together with the form of the rings, should determine 
the position of the long axis of the chromosomes. The tufts of 
spindle fibers are attached to each individual of the tetrads, and 
transverse or reducing division of the chromosome results as 
these are drawn away from the nuclear plate. In many cases 
the sixty-four tetrads, thirty-two to each pole, move as distinct 
individuals, so that longitudinal, as well as transverse division, 
occurs in the first mitosis of the mother cell nucleus. But while 
transverse division occurs during the first mitosis of the nucleus, 
longitudinal division of the chromosome takes place first. The 
peculiarity of Arisaema, then,.is that, while longitudinal division 
precedes transverse division of the chromosome, both divisions 
occur during the first or heterotypic division, and the real reduc- | 
tion follows soon the pseudo-reduction in the heterotypic 
division, 
The only other account of a reducing division in the first 
mitosis which I have noticed is that by Korschelt in the study 
of the development of the egg of the annelid Orphryotrocha, 
quoted by Wilson in “The cell in development and_inheri- 
tance,” p. 201. During the first mitosis in oogenesis, the spirem 
segments into four chromosomes, which is the normal number 
in the somatic cells. These split, and then-the pairs fuse 
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