136 Flowers and tJieir Pedigi^ees. 



produce relatively strong and hearty seedlings. The 

 two cases are exactly analogous to the effects of 

 breeding in and in or of an infusion of fresh blood 

 among races of men and animals. Hence it naturally 

 happens that those plants whose organisation in any 

 way favours the ready transference of pollen from one 

 flower to another gain an advantage in the struggle for 

 existence, and so tend on the average to thrive and to 

 survive ; while those plants whose organisation renders 

 such transference difficult or impossible stand at a con- 

 stant disadvantage in the race for life, and are liable to 

 fall behind in the contest, or at least to survive only in 

 the most unfavourable and least occupied parts of the 

 vegetal economy. Familiar as this principle has now 

 become to all scientific biologists, it is yet so absolutely 

 necessary for the comprehension of the present ques- 

 tion, whose key-note it forms, that I shall make no 

 apology for thus once more stating it at the outset 

 as the general law which must guide us through all 

 the intricacies of the development of wheat. 



Our primitive ancestral lily, not yet a lily or any- 

 thing else nameable in our existing terms, had thus 

 to start with, one triple set of ovaries, and about three 

 triple sets of pollen-b6aring stamens ; and to the very 

 end this triple arrangement may be traced under more 

 or less difficult disguises in every one of its numerous 



