Primitive A agio sperms. 157 
stem-bud is completely dominated by the lateral member, which embraces 
and at last arches over it. This lateral member is of course the single 
cotyledon, which becomes apparently terminal in the mature embryo, for 
it manages to push the stem-apex to one side. 
In the interpretation of their results, Hegelmaier and Schmid consider 
one possibility only — the formation of a single cotyledon from the original 
pair by suppression of the second. Hegelmaier is inclined to localize the 
missing cotyledon in that region of the ring where growth first ceases. 
A projection is formed there from which a sheath-like organ is developed. 
Schmid, however, considers the projection in this place as equally likely 
to represent the sheath of the single cotyledon only, and he does not attach 
much importance to the single abnormal embryo of Carum Bulbocastanum 
figured and described by Hegelmaier in which this projection is almost 
as large as the still rudimentary cotyledon ( 37 , PL VII, Fig. 41). Solms- 
Laubach definitely refused to consider a similar formation in the embryo 
of Tamus communis as anything more than the rudiment of the cotyledonary 
sheath ( 82 , pp. 85, 86, and Figs. 29-33). 
Sterckx ( 83 ), on the other hand, dealing with Ranunculus Ficaria only, 
is much influenced by the bilobed blade of the fully expanded cotyledon 
(p. 45 and Figs. 176, 177, PI. XV). The peculiar venation of this blade 
suggests — as he points out — the fusion of two leaves into a single member. 
The embryo in his figures also shows a slight but quite definitely bilobed 
structure (loc. cit., Fig. 156). He concludes that the single cotyledonary 
member is in fact a fusion of the two cotyledons which we attribute to the 
ancestral Ranunculus . 
Now, if we agree in this explanation of the single cotyledon of 
Ranunculus Ficaria , we may equally well interpret the similar structure 
of the embryo in Corydalis cava and Carum Bulbocastanum in the same 
way. With the exception of the slightly bilobed cotyledon found in the 
embryo of Ranuncuhts Ficaria , the development of all three is precisely 
alike. 
The position of the first leaf, which is opposite the cotyledon, is also 
an argument for Sterckx’s theory. For, if the single cotyledon represents 
a pair fused along one margin, the first leaf would stand in its proper place 
relatively to that pair. But if the cotyledon represents one of a pair of 
which the other has disappeared the abortive cotyledon would stand 
behind the first leaf, which could not be its original position. 
The truth is, however, that there is nothing in the development of 
the embryo in any one among the three Pseudomonocotyledons just 
described which will decide between the rival theories. So far as the 
evidence goes, the single cotyledon in all three might be derived from the 
ancestral pair either by suppression of one cotyledon or by union of the two 
into a single member. 
