Chromosomes in Living Organisms . 313 
of division exhibited by the mother-cells of the ova and 
spermatozoa of those animals in which they have been 
minutely investigated, doubtless depends upon homology : 
the divisions into four after the process of reduction must 
have a common cause. The analogy is very striking between 
the much-discussed processes of splitting of the chromosomes 
in the mother-nuclei of animals, and the processes described 
by Farmer as taking place in the spore-mother-cells of Liver- 
worts : for in Pallavicinia and in Anenra the number of 
chromosomes requisite for the two following divisions is 
provided at one and the same time in the nucleus of the 
spore-mother-cell. In these Liverworts, indeed, the abbre- 
viation is the more marked, since a quadripolar nuclear spindle 
is formed, and the products of the longitudinal splitting of the 
chromosomes are simultaneously distributed to the four 
daughter-nuclei. It is of special purpose that I cite this 
particular case, for it alone, in plants, corresponds to the 
phenomena observed in animal ova : in these plants, as in 
animals, the double division follows on the process of reduction, 
and introduces the diminished number of chromosomes 
characteristic of the sexual cells. It must, however, be pointed 
out that the nuclear divisions with multipolar spindles to be 
found in the developing endosperm 1 of Angiosperms and in 
pathogenic tissues of animals, are not comparable with those 
here alluded to. For in those cases the division is not 
preceded by any internal changes in the nucleus ; the number 
of the poles is variable, even accidental ; and the number of 
the chromosomes distributed to the daughter-nuclei is not 
always the same. 
I have already suggested that, in cases in which the 
product of the sexual act directly gives rise to the original 
generation, a process of reduction taking place at the com- 
mencement of germination is to be anticipated. It is possible 
to interpret in this sense the observations of Klebahn and 
Chmielewsky on the process of the germinating zygotes of 
1 Zellbildung unci Zelltheilung, 3. Aufl., 1880, p. 18. 
