No. 457.] EMBRYO OF THE ANGIOSPERMS. I7 
dence, that the angiosperms. are monophyletic ; that their most 
recent common ancestors were Angiosperms. 
ARE COTYLEDONS TRUE LEAVES? 
The oldest and at all times the favorite interpretation of coty- 
ledons is that they are arrested or metamorphosed foliage leaves. 
The antiquity of this view as well as the basis on which it was 
founded is well set forth in the following quotation from Sachs’ 
History of Botany: “We see that Cesalpino uses the same 
word * folium" without distinction for calyx, corolla and ordinary 
leaves ; just as he and Malpighi a hundred years later unhesitat- 
ingly regarded the cotyledons as metamorphosed leaves. In 
fact the envelopes of the flower and the cotyledons approach so 
nearly to the character of leaves that every unprejudiced eye 
must instinctively perceive the resemblance.” 
From time to time various authors, while accepting the foliar 
theory of cotyledons in its general application, have concluded 
that the analogous structures in certain plants are not true coty- 
ledons but organs of a different morphological value. The 
scutellum of the grasses, which is now commonly considered a 
cotyledon, has been variously interpreted.? Richard (’11) dis- 
tinguished as * Embryons macropodes’ the embryos of the 
grasses, Nelumbo, Ruppia, Hydrocharis and Zostera. The 
scutellum of the grass embryo and the cotyledonary lobes of the 
embryo of Nelumbo he considered homologous to the massive, 
macropodous portions (l’'hypoblaste) of the embryos of Ruppia, 
Zostera and Hydrocharis. This hypoblast he interpreted as a 
lateral outgrowth or expansion of the radicle. Schaffner (:04) 
compares the embryos of the Nymphzacez with those of Rup- 
pia, Zostera and Halophila. He reiterates Richards conclusions 
concerning the homology of the cotyledonary lobes with the 
macropodous body which he terms a hypocotyledonary expansion. 
Nageli (78), however, early ventured the opinion that “ Der 
Embryo der Gefásskryptogamen und der Phanerogamen ist kein 
Caulom sondern ein Thallom, wie das Mooseporangiun, aus dem 
! English translation 1890, p. 
2 Vide Bruns ('92) and nds (:00). 
