* 
18 THE AMERICAN NATURALIST. (VoL. XXXIX. 
er phylogenetisch hervorgegangen ist; die Samenlappen sind 
keine Phyllome, sondern Thallomlappen. An dem Embryo tritt 
als neue Bildung der Stengel auf." 
In a lecture delivered at the Minnesota Seaside Station in 
June, 1901, and since published in the Year Book of the station, 
the writer suggested that cotyledons are not arrested leaves but 
are primarily haustorial organs, originating phylogenetically as 
the nursing-foot in the Bryophyta and persisting throughout the 
higher plants. 
Balfour, in his presidential address to the Botanical section of 
the British Association, September meeting, 1901, said, ** We 
ought, I think, to look upon the embryo of the angiosperms as 
a protocorm of embryonic tissue adapted to a seed life. Under 
the influence of its heterotropic nutrition and seed environment. 
it may develop organs not represented in the adult plant, as we 
see in, for instance, the embryonal intra-ovular and extra-ovular 
haustoria it often possesses. There is no reason to assume that 
there must be homologies between the protocorm and the adult 
outside an axial part with its polarity. There may be homolo- 
gous organs. But neither in ontogeny nor in phylogeny is there 
sufficient evidence to show that the parts of the embryo are a 
reduction of those of the adult. .... I cannot pursue the subject 
here nor discuss the view of the cotyledons as either ancestral 
leaf-forms or arrested epicotylar leaves. The analogies with 
existing Pteridophytes that are cited are not pertinent, for there 
is no evidence that angiosperms have that ancestry, or indeed 
that their phylogeny was through forms with free embryos. 
Nor is the fact of resemblance between cotyledons and epicoty- 
lar leaves and the existence of transitions between them con- 
vincing. That the cotyledons, primarily suctorial organs, should 
change their function and become leaf-like under the new condi- 
tions after germination is no more peculiar than that the hypo- 
cotyl should take the form of an epicotylar internode from which 
it is intrinsically different as the frequent development upon it 
of hypocotylar buds throughout its extent shows.” 
While each of the above authors expresses a distinct interpre- 
tation quite at variance with those offered by the others, still all x 
declare alike on our present point of discussion, that cotyledons. 
are not morphologically foliage-leaves. 
