596 ON SEEDLINGS 



muricata (fig. 384) differs in having somewhat larger cotyledons 

 and two pairs of opposite leaves, the first pair being obsoletely 

 trilobed at the apex and seven- to nine-nerved. Trichosanthes 

 palmata (fig. 382), T. Anguina, and Cucumis utilissimus have 

 obovate-spathulate, three- to five-nerved cotyledons of much 

 greater size than those of Momordica. The first named has 

 the first leaf reniform and inserted close to the cotyledons 

 owing to the non-elongation of the first internode. The 

 primary leaves of Trichosanthes Anguina are cordate and also 

 alternate, but all the intemodes are elongated. A very re- 

 markable instance of variability occurs in this species, for 

 although the usual type is that just given, seedlings occur in 

 which the two first leaves are opposite, and in rare cases 

 there are three cotyledons followed by three leaves also in a 

 whorl. 



A second type is that in which the cotyledons are oblong 

 or obovate-oblong, and narrowed at the base into short, more 

 or less channelled petioles. They are also three- to five-nerved, 

 although the intermediate pairs of nerves are not strictly 

 basal. 



Cucumis sativus (fig. 386) is an instance with entire 

 cotyledons. The first leaf is cordate, incipiently lobed, and is 

 inserted on the axis close to the cotyledons, a circumstance of 

 very frequent occurrence, as for instance in Trichosanthes 

 palmata mentioned above and Acanthosicyos horrida (fig. 383), 

 Citrullus Colocynthis, Cephalandra palmata (fig. 388), Bryonia 

 laciniosa (fig. 390) and Cionandra. In all the last five the 

 cotyledons are large and more or less deeply emarginate. The 

 primary leaves of most of them are very characteristic of the 

 Order and show a greater or less amount of evolution. A 

 good instance is that of Citrullus Colocynthis, the first leaf 

 of which is rotund, truncate at the base, and obscurely 

 crenate ; the second is oblong-cordate, five-nerved and 

 shallowly five-lobed, followed by others that are more deeply 

 and sharply divided. The first leaf of Cephalandra palmata 

 is cordate ; the second and third palmately three- to five- 

 nerved and -lobed. The first six leaves of Bryonia laciniosa 

 are five-nerved and deeply tripartite, the divisions being 

 narrow from the third leaf onwards. The most striking case 



