302 
N. Bancroft. 
according to their habitat on land or by, or in, water, The forms 
subjected to an aquatic or moist habitat became degenerate 1 owing 
to the weakening effect of water by saturating the protoplasm. This 
is shown in the case of division and fenestration of leaves of aquatic 
plants, loss of secondary growth by means of a cambium, and in 
the case of Monocotyledons, by complete loss of one cotyledon. 
Henslow maintains—apparently in answer to Miss Sargant’s criticism 
that there is no evidence of suppression—that the second strand in 
the cotyledon of that author’s so-called primitive Monocotyledons, 
is the last relic of the cotyledon which has been otherwise totally 
arrested (31, p. 743). After the aquatic Angiosperms had been 
subjected to weakening conditions through many generations, the 
effect of such conditions became fixed and hereditary, so that at the 
present time, Monocotyledons are unable to adapt themselves 
completely to land conditions in competition with the Dicotyledons— 
hence the retention of an aquatic habit by so many of them. 2 
In support of heterocotyly, Compton (11, p. 802) quotes the 
case of Ranunculus Ficaria. It will be remembered that according 
to Miss Sargant (59, p. 75), this is a case of asymmetrical 
syncotyly, or union of the cotyledonary petioles by one edge only 
(see also Sterckx, 66, p. 42). But according to Compton, the 
balance of evidence—such as vascular anatomy and venation of the 
cotyledonary blades—is in favour of the view of Hegelmaier (29) and 
Schmid (63, p. 211) that the seed-leaf in Ranunculus Ficaria is a 
single organ. The evidence applies to Corydalis spp., Canon 
Bulbocastanuni, Pinguicula spp., Abvonia spp. Compton concludes 
that in these cases it is difficult to decide whether complete 
suppression of one cotyledon accounts for heterocotyly, or whether 
the missing cotyledon has been retarded in development, and now 
appears as the first foliage leaf. 
Lotsy (42, p. 624) broad-mindedly admits the origin of mono- 
cotyly in any of the ways described by various writers. He thinks, 
however, that the case of syncotyly is less well-established than that 
of heterocotyly. 3 
1 Cf. de Vries (16, p. 15), who insists on the degenerate nature of 
Monocotyledons. 
3 A comparison of Henslow’s view of the origin of Monocotyledons with 
that of Miss Sargant, shows that, according to Henslow, the aquatic habitat is 
primarily the cause of the evolution of Monocotyledons ; while according to Miss 
Sargant, it is largely the result of the development of a monocotyledonous 
condition. 
3 Guillaumin (25, p. 232) also admits that monocotyly may have arisen by 
fusion of two cotyledons, or by suppression of one. 
