364 BRITISH FLOWERING PLANTS chap. 



then, as I believe, to the curvature of the leaf, owing to 

 the shortness of the bud in comparison with the length 

 of the leaf. The young leaf is not only curved, it is 

 wrapped round the interior leaves. The result of this 

 is that one side of the leaf is folded within the other ; 

 the one therefore has more space than the other. The 

 two sides of the leaf are, in fact, differently situated, 

 and this, I believe, accounts for the second point — 

 namely, the want of symmetry. The obovate form is 

 an advantage in consequence of the way the leaves 

 diverge from the stalk. I think, then, that the 

 explanation I have suggested accounts for all these 

 points, and beautifully explains the peculiar form as- 

 sumed by the leaf 



The arrangement of the seeds is also very interesting. 

 Fig. 252 is a diagram of a Nut with the parts somewhat 

 separated from one another so as to show the relations 

 more clearly. The micropyle (m) is at the apex of 

 the seed.^ The ovule, however, is not straight and 

 orthotropous, which would be, or at any rate seem 

 to be, the simplest arrangement. Quite the contrary, 

 for we find a long placental axis (pi), which extends to 

 the apex of the Nut, and from which starts a raphe (r), 

 which returns about half-way back again to the place 

 where the true attachment or chalaza (ch) is situated. 

 I have in vain endeavoured to discover or imagine any 

 circumstances which would render this complex arrange- 

 ment specially adapted to present conditions. It would 

 seem as if it would be simpler, and give Nature less 

 trouble, if the ovule sat directly with its base on the 

 stalk, thus doing away with both the placental axis 

 (pZ) and the raphe (r). 



This view is strengthened by the fact that such an 

 arrangement has actually been nearly attained by the 

 Oak. The ovule in this genus is theoretically ana- 

 tropous, but the placental axis and the raphe are both 

 greatly shortened (Fig. 251), so that the distance 

 which the nourishment has to traverse is much less, 



^ Avebury (Lubbock), On Seedlings, ii. 



