A CONTRIBUTION 



TO OUE 



KNOWLEDGE OF SEEDLINGS 



INTRODUCTION. 1 



FORMS OF LEAVES. 



I have elsewhere 2 called attention to the forms of leaves, and 

 discussed the causes to which we may ascribe the endless 

 differences which they present. Vertical leaves, for instance, 

 are generally long and narrow, horizontal ones have a ten- 

 dency towards width, which brings the centre of gravity 

 nearer to the point of support. Wide leaves, again, are some- 

 times heart-shaped, sometimes palmate. The former shape is 

 obviously that which would arise if a linear leaf were gradually 

 widened at the base ; and I have pointed out that in many 

 species with palmate leaves for instance, species of Passiflora, 

 Cephalandra, Hibiscus, &c. the first, or few first, leaves are 

 entire and more or less cordate. The cordate form, then, ap- 

 pears to be the early, the palmate a later form. But how has 

 the palmate form arisen ? 



The origin is perhaps connected with the manner in which 

 the leaves are folded up, more or less like a fan, into the bud, 

 so as to save space. 



Another advantage perhaps is that in cordate leaves with 



1 This Introduction is taken from the Journal of the Linnean Society 

 (Botany), vol. xxii. and vol. xxiv. 



2 Flowers, Fruits, and Leaves (Nature Series), Macmillan & Co. See also 

 various papers in the Journal of the Linnean Society. 



