BRIEFER ARTICLES. 
THE EARLY HISTORY OF ANGIOSPERMS. 
THE paper lately published by Mr. Harotp Lyon on the embryo of 
angiosperms' gives a clear account of existing views on the race-history 
of monocotyledons and dicotyledons. In the course of his argument 
Mr. Lyon has referred to my own work on the subject in very generous 
terms, while giving in greater detail than before the arguments which had 
already led him to the opposed conclusion. We are, as before, in complete 
agreement as to the field of battle. We both hold that monocotyledons 
and dicotyledons come from a common stock, and that the single cotyledon 
of the one is strictly homologous with both cotyledons of the other. But 
on the question of the comparative antiquity of these two classes, we start 
from opposite ends of the lists. I do not propose to discuss the points on 
which we differ. The evidence on both sides has been published, and also 
our respective interpretations. Those interested in the question are in a 
position to form their own judgment on it. The issue will be determined 
by the results of future research. But Mr. Lyon’s lucid statement of the 
case has shown-me that my own is obscure in two points, and I wish to 
take the first opportunity of restating them. 
First I wish definitely to disown the suggestion that the fusion of two 
ancestral cotyledons might have taken place within the seed where they 
were acting as sucking organs. This appeared in my first sketch of the 
whole hypothesis, published in May, 1902.2, In later papers the fusion 
of the cotyledons is attributed to the reduction of assimilating organs 
characteristic of geophilous seedlings in their first season, a second sug- 
gestion, inconsistent—as Mr. Lyon has pointed out—with the first, which 
is implicitly abandoned. It would have been clearer to state definitely, 
as I do here, that—if we consider monocotyledons as derived from a dicoty- 
lous stock by adaptation to a geophilous habit—the fusion of two cotyledons 
Lyon, Harotp L., The embryo of the angiosperms. American Naturalist 
39:13-25- 1905. 
2 The origin of the seed-leaf in monocotyledons. New Phytologist 1:107-113- 
pls. 2. 1902. 
3A theory of the origin of monocotyledons. Ann. Botany 17:1-92- pls. I-7- 
1903. The evolution of monocotyledons. Bot. GAZETTE 37:325-345- 1904- 
JUNE] 420 
