The President's Address. By Lord Avebury. 303 



which grows near streams and lakes, is light, and probably carried 

 mainly by water. 



The arrangement of the seeds is also very interesting. Fig. 84 

 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, 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 am not pre- 

 pared to suggest 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 arrangement has actually 



m. 



Fig. 84. 



been nearly attained by the Oak. The ovule in this genus is theo- 

 retically anatropous, but the placental axis and the raphe are both 

 greatly shortened, 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 neutralised 

 them. Is it fanciful to imagine that some ages hence the Oak may 

 be practically orthotropous ? (fig. 85). 



But why should these species be anatropous if it is an 

 advantage to be orthotropous I 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 comes to anything. They can, 

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

 Nut and Beech {Fagus), or, as in the Oak, near the base. Their 

 presence appears to indicate that these species are descended from 

 ancestors, the fruit of which was composed of several cells, each 

 with more than one seed — a state of things, therefore, very unlike 

 the present, and in which the anatropous condition would be an 



