MORPHOLOGY AS A FACTOR IN DETERMINING RELATIONSHIPS II3 
rapidly accumulating to show that the former group has been derived 
from the latter. Several writers have expressed this belief, but they 
have reached their conclusions from rather different points of view. 
I refer particularly to the recent contributions by Henslow and by 
Ethel Sargent. Miss Sargent's paper entitled "A Theory of the 
Origin of Monocotyledons, founded on the Structure of their Seed- 
lings" points out that "the cotyledon of Anemarrhena, a lihaceous 
genus, contains two massive bundles which together form a tetrarch 
stele in the primary root" ; and she interpreted this as probably due to 
"a fusion of two seed-leaves in some remote ancestor to form the single 
cotyledon of Anemarrhena.'' Seedlings of other Liliaceous genera were 
also examined, but this one she regards as representing a rather 
primitive type. Miss Sargent contrasts this condition with the 
condition shown by certain dicotyledonous plants, e. g., species of 
Anemone, Delphinium, Ranunculus, Trollius, Eranthis, etc., ''pos- 
sessing seed leaves which are partially united, sometimes by one 
margin only, but more often by both." The conclusion therefore being 
that the monocotyledons have been derived from the dicotyledons 
through a fusion of the two cotyledons into one. 
In this connection I may call attention to a very suggestive paper 
by Coulter and Land in a recent number of The Botanical Gazette; 
they record the results of a morphological study of seedlings of Aga- 
panthus umhellatus, a South American amaryllidaceous plant, seedlings 
of which were found to possess more or less indifferently one or two 
cotyledons. This study has been continued, and a paper by the same 
authors was read by Professor Coulter at the recent celebration of the 
25th Anniversary of the Missouri Botanical Garden. Although this 
second paper is not yet published Professor Coulter stated, "The 
general conclusion is that monocotyledony is simply one expression 
of a process common to all cotyledony, gradually derived from dico- 
tyledony, and involving no abrupt transfer of a lateral structure to a 
terminal origin." 
In other words morphological evidence has been presented by Miss 
Sargent that monocotyledony has resulted by a fusion of two coty- 
ledons and according to Coulter and Land by the reduction and disap- 
pearance of one cotyledon. In either case the phenomenon is inter- 
preted as indicating the origin of the monocotyledons from the 
dicotyledons. 
While recent studies have been concerned mainly in determining 
