39G sin J. LUBBOCK — phytobiological obsertations. 



a certain cliange, whicli lias been of superior importaiicej tas 

 involved a minor evil. 



The Oalv, Beech, ISTut, &c. afford vis a very interesting series of 

 species. Fig! 132 represents a diagram of a nnt Avitli the parts 

 somewhat separated from one another, so as to &"ho^\- the relations 

 more clearly. The micropyle (?>?) is at the apex of the seed. The 

 ovule, however, is not straight and orthotropous, which would he, 

 or at any rate seem to be, the simplest arrangement. Quite the 

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

 apex of the nut, and from which starts a rajihe (r), which returns 

 about halfway back again to the place where the true attachment 

 or chalaza {cli) is situated. I have in vain endeavoured to discover 

 or imagine any circumstances which would render this complex 

 arrangement 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 {pi) and the raphe (r). 



This view is strengthened by the fact that such an arrange- 

 ment has been in fact nearly attained by the Oak. The ovule in 

 that genus is theoretically anatropous, but the placental axis and 

 the raphe are both greatly shortened (fig. 131), so that the 

 distance which the nourishment has to traverse is much less, 

 though the actual place of attachment remains the same. The 

 Oak in fact seems to have appreciated the difficulties of the 

 situation, and to have in great measure neutralized them. Is it 

 fanciful to imagine that some ages hence the Oak may be prac- 

 tically orthotropous ? 



But why should these species be anatropous if it is an 

 advantage to be orthotropous ? On this question some light is 

 thrown by the fact that while one seed only comes to maturity, 

 the ovary contains originally several cells each with one or two 

 ovules, though none of the others come to anything. They can, 

 however, easily be seen, either at the apex of the seed, as in the 

 Kut (fig. 132, o\ %ech {Pagm), «S:c., or, as in the Qak (fig. 131, o), 

 near the base. Their presence appears to indicate that these 

 species are descended from ancestors the fruit of which was com- 

 posed of several cells, each with more than one seed — a state of 

 things therefore very unlike the present, and when the anatropous 

 condition would be an advantage. If this view be correct, the 

 structure of the fruit in the Nut, Beech, &c, becomes peculiarly 



