142 BOTANICAL GAZETTE [FEBRUARY 
2. EVIDENCE FROM THE REDUCTION OF CHROMOSOMES.—The 
reduction of chromosomes is a phenomenon so complex and so unique, 
and at the same time so essentially identical in plants and in animals, 
that any adequate theory must be applicable to both kingdoms. 
In plants the reduction always occurs during the first two divisions 
of the spore mother-cell, whether the plant be homosporous or 
heterosporous. In animals the reduction occurs during the first two 
divisions of the primary oocyte and primary spermatocyte. The 
structural character of the mitoses are too well known to need any 
review at this time. According to STRASBURGER? the reduction of © 
chromosomes indicates a return to the more primitive gametophytic 
generation, and this view is quite generally accepted by botanists. 
I am aware that zoologists distinguish somatic and germ plasm, 
and that the application of this theory of alternation with its terms 
gametophyte and sporophyte (or rather similar terms, since “ phyte” 
is obviously unsuitable) would cut the line of germ plasm, leaving 
part in one generation and part in the other. The sporogenous tissue 
of plants is quite analogous to the germ plasm of animals, and yet 
most botanists have no hesitation in assigning it to the sporophyte 
and in regarding the mother-cell as the first term of the gametophytic 
generation. The gametophytic generation—whether long as in the 
liverworts or short as in the angiosperms—is characterized by the 
reduced number of chromosomes; the sporophyte, except possibly 
in cases of parthenogenesis, contains double the number of chromo- 
somes found in the gametophyte. We should recognize two gener 
ations in animals, characterized respectively by the reduced and the 
double number of chromosomes. 
COROLLARY. 
It is obvious that this theory, if well founded, affects not only 
the application of sexual terms in plants, but also our notions in regard 
to the nature of sexuality. It is hardly necessary to say that most 
terms relating to sexuality in plants have been borrowed from zoolo- 
gists. Many botanists, especially the more rigid morphologists, 
have attempted to confine sexual terms to the gametophytic genet 
2 STRASBURGER, E., The periodic reduction of chromosomes in living organisms: 
Ann. Botany 8:281-316. 1894. 
