24 The Botanical Gazette. [January; 
entiation first took place. This reduced number which is de- 
termined in the spore mother-cells in angiosperms persists in 
all subsequent divisions to the formation of the generative 
nuclei, involving usually four divisions in the history of the 
male nucleus, and five in the case of the female, although in 
the latter case the divisions may be three, four, five or more. 
It is evident that the attempt to establish homologies between 
the successive divisions preceding the formation of the two 
generative nuclei is futile; and it is equally worthless to claim 
on physiological grounds the necessity for a certain definite 
number of nuclear divisions that the two nuclei may be 
brought to the same bulk. The reduction in the number of 
chromosomes, therefore, is not to be regarded as a prepara- 
tion for the sexual act, but it marks the beginning of a new 
generation which comes into existence with the primitive 
number of chromosomes, of which generation the spore mother- 
cell is the initial cell. 
chromosomes is found long before the development of archego- 
nia has begun. 
This further emphasizes the fact that the number of succes- 
sive nuclear divisions which precede the generative nucleus is 
very variable and holds no relation in the parallel male and 
female generations. In pteridophytes and bryophytes the 
number of chromosomes is hard to determine on account 0 
the small nuclei of the latter and the great number of chromo- 
somes of the former. In some ferns, however, as Osmunda 
regalis, the number of chromosomes is as small as in phaner- 
ogams, and in this case the reduction appearing in the nu- 
cleus of the spore mother-cell persists throughout the prothal- 
lium, and is half the number found in the sporophyte. Among 
bryophytes the counting of chromosomes has been accomp- 
lished in a liverwort, which showed four chromosomes in 
gametophyte nuclei and eight in sporophyte nuclei, the num- 
ber four appearing first in the spore mother-cell. No count- 
ings of the chromosomes in alge and fungi have been made, 
due partly to the difficulty of the operation and partly to the 
lack of appreciation of its importance. That the number of 
chromosomes in these lower cryptogams is definite Stras- 
burger believes from the few preparations he has examined. 
