ASYMMETRY OF LEAVES 



123 



horrida, Sophora japonica, Vitex Agnus-castus.' The relationships of 

 position of the leaflets within the bud may be most different, and 

 consequently an influence of gravity cannot exist. 'A careful investigation 

 shows however that a difference in the size of the sides of the leaflets 

 in the closed bud does not exist in all observed cases ; no marked 

 constant difference, nor indeed any difference at all, in the breadth of 

 these sides can be shown (established in Vitex, Staphylea, Rosa, 

 Pterocarya ....). The difference in the growth of the sides of the 

 leaflets only appears whilst the unfolding of the bud is going on, and 

 during this the side of the leaflets which subsequently is least developed 

 is always the higher with its edge turned towards the zenith.' 



FIG. 72. Bauhinia species. Apex of the shoot. The Iraves FIG. 73. Chelidonium majus. Asymmetric 



have two leaflets strongly asymmetric from an early period ; at configuration of the leaf-lobes. Reduced 

 the base of each leaf are two stipules. about half. 



I have no doubt whatever that this view is altogether untenable; 

 what is stated in the last sentence is not founded upon fact. I agree 

 with Spencer when he says 1 : 'How far such differences of develop- 

 ment are due to the positions of the parts in the bud ; how far the 

 respective spaces available for the parts when unfolded affected them ; 

 and how far the parts are rendered unlike by unlikenesses in their 

 relations to light ; it is difficult to say.' The features exhibited by the 

 species of Bauhinia represented in Fig. 72 permit us to assume that an 



' Herbert Spencer, Principles of Biology, ii. p. 



