Sexual Nuclei in Li Hum Mart agon. 463 
time. Later on, as the coils of the daughter nuclei open out, 
the number of drops increases, and some are found inside the 
nuclei (Fig. 25). There can be little doubt that we here have 
drops of nucleolar substance from which the new nucleoli are 
being reconstructed. The coils of chromatic ribbon are at 
first coloured uniformly like chromatin, but later on they 
show the familiar structure of a linin ribbon bordered with 
dark dots (Fig. 25). No doubt the dots are granules of 
chromatin, but their identity with those bordering each seg- 
ment of the immature chromosome (Fig. 19 a) cannot be 
traced. The cell-plate is still clear between the nuclei. It 
finally disappears when they have passed into the resting- 
stage (Fig. 26). 
We may now sum up the conclusions drawn from our 
examination of the first division of the embryo-sac nucleus. 
The chromosomes have been identified with lengths of the 
ribbon so clearly shown in the well-known spirem stage. 
Each segment of a single chromosome represents one of the 
two parallel rows of granules found in such a length of 
ribbon. It has never been doubted that these arose by fission 
of a single row at an earlier stage 1 , and the history of their 
development confirms this view. The karyokinesis therefore 
which separates the two segments of each chromosome from 
each other does in fact divide the chromosomes longitudinally. 
The history of the second longitudinal fission — that which 
takes place within each segment— -is not so satisfactorily 
completed. It is not certain that this fission persists in the 
mature chromosome (vid. ante, p. 461). Even supposing that it 
does, and that the chromatin granules mentioned as appearing 
in the dispirem can be identified with the granules of the 
immature chromosome, all trace of fission is again lost in 
the resting-stage of the daughter nuclei. It is not impossible 
indeed that the slender thread of this stage bears a double 
row of granules, but there is no evidence that it does so. 
The existence of four rows of granules in the immature 
1 Guignard, 1. c., p. 183. 
