260 PLANT-BREEDING 



and most reliable guide. For numerous determinations 

 have taught that large seeds have thinner integuments than 

 smaller ones. This rule holds good for grains and peas 

 and probably for all agricultural crops, and even for flowers 

 and wild plants the same relations prevail. The size of the 

 germ and albumen and the development of the surrounding 

 layers are evidently dependent on the same influences. 

 Individual strength of the variety, or a better nourishment 

 of the single plants will cause both of them to increase. 

 But the measure of the increment will be different for them, 

 and therefore their proportion in weight and volume will 

 be affected by the change. The relation is the same as that 

 which we have studied in our last chapter for the size of 

 the flowers and the length of the styles in the evening prim- 

 roses. Or, in other words, favorable conditions will promote 

 the development of the inner nutritive parts of the seeds in 

 a higher measure than that of the less digestible coverings. 

 The preference commonly given to large seeds may be 

 explained by the evidence afforded. But the detailed cor- 

 relation is not the only one. On the contrary, the size of 

 the seed is correlated with its development during the ger- 

 minating period, and, through this, has an influence on the 

 individual strength and size of the whole plant. Moreover, 

 larger seeds are known to be more equal in size, the smaller 

 specimens which are so common in non-selected samples, 

 failing in them. This conformity results in simultaneousness 

 of germination and development, two of the weightiest factors 

 for a regular growth of the crop. Especially they determine 

 whether at the -time of the harvest all ears or all pods will be 

 duly ripe, or whether a larger or smaller part of them will be 

 lost. Ripening too early, an ear may lose its kernels before 

 the harvest, whilst ripening too late it is of no use at all. 

 A simultaneous development, therefore, is one of the most 

 desirable qualities in cultivated plants, and this may be 



