THE PEDIGREE OF WHEAT. 663 



plant, or at least of another blossom on the same stem. Seeds fertil- 

 ized by pollen from their own flower, as Mr. Darwin has shown, pro- 

 duce relatively weak and sickly seedlings ; seeds fertilized by pollen 

 from a sister plant of the same species 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 

 organization in any way favors 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 organization renders such transference difficult or impos- 

 sible stand at a constant disadvantage in the race for life, and are 

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

 most unfavorable 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 

 question, 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 anything else nam- 

 able in our existing terms, had thus, to start with, one triple set of 

 ovaries, and about three triple sets of pollen-bearing stamens ; and to 

 the very end this triple arrangement may be traced under more or less 

 difficult disguises in every one of its numerous modern descendants. 

 No single survivor, however, now represents for us this earliest ideal 

 stage ; we can only infer its existence from the diverse forms assumed 

 by its various divergent modifications at the present day, all of which 

 show many signs of being ultimately derived from some such primor- 

 dial and simple ancestor. The first step in advance consisted in the 

 acquisition of petals, which are now possessed in a more or less rudi- 

 mentary shape by all the tribe of trinary flowers, or at least, if quite 

 absent, are shown to have been once present by intermediate links or 

 by abortive rudiments. There are even now flowers of this class 

 which do not at present possess any observable petals at all ; but these 

 can be shown (as we shall see hereafter) not to be unaltered descend- 

 ants of the prime type, but on the contrary to be very degraded and 

 profoundly modified forms, derived from later petal-bearing ancestors, 

 and still connected with their petal-bearing allies by all stages of in- 

 tervening degeneracy. The original petalless lily has long since died 

 out before the fierce competition of its own more advanced descend- 

 ants ; and the existing petalless reeds or cuckoo-pints, as well as the 

 apparently petalless wheats and grasses, are special adaptive forms of 

 the newer petal-bearing rushes and lilies. 



The origin of the colored petals is almost certainly due to the selec- 

 tive action of primeval insects. The soft pollen, and perhaps, too, the 

 slight natural exudations around the early flowers, afforded food to 



