THE ABORTION OF OVULES 359 



two ovules in a cell fail early, the growth of the cell does not 

 proceed far. Here it is evident that the initial growth of 

 the fruit is determined by the fertilising process, but its later 

 growth depends on the seed. 



In Aquikgia each carpel contains on the average thirty ovules, Aquilegia. 

 of which twenty-five mature as seeds, four abort early, and one 

 fails after proceeding a little further in its growth. Most of the 

 aborted ovules usually occur in a clump at the lower end of the 

 follicle. This may be connected with the fact that in the 

 flower the ovules at the base of each carpel are exposed by 

 the gaping of the carpellary walls, and remain exposed during 

 much of the ripening of the fruit. 



The tremendous waste of ovules, or rather of young seeds, Ravenala 



A 



in the sub-drupaceous capsule of Ravenala madagascariemis has SUienS&T 

 already been alluded to in Chapter XIII. in connection with 

 the dehiscence of the fruits. Of the plants with many-ovuled 

 flowers included in the table near the close of this chapter 

 there is not one that comes near Ravenala in this respect, five- 

 sixths of the ovules at a very moderate computation failing to 

 mature as seeds. It would seem, however, that nearly all of 

 them first reach an early stage of seed-growth. One cannot 

 help thinking that this large sacrifice of seeds is due to the 

 great pressure exercised by the growing seeds upon each other 

 within the stony, and for a long time unyielding, walls of the 

 endocarp. When dehiscence at length occurs, the fruit-cavity 

 is seen to be full of aborted seeds, 2 to 5 millimetres in size, 

 with only a few large matured seeds. 



Although the beading of legumes is well marked in some The beading 

 genera, as in Erythrina and Sophora, a slight tendency to the 

 moniliform type is frequently displayed in other leguminous 

 genera with long pods, such as Faba, Genista, Phaseolus, 

 Poinciana, etc. Though abnormal in such cases, it is due to 

 the same influences that operate in the typical moniliform pod, 

 namely, the early abortion of ovules and the early failure of 

 seeds in the body of the fruit. In some other cases, as in those 

 of the Laburnum and of Albizzia^ the tendency is pronounced ; 



