DEGENERACY OF FLOWERS. 275 



experiments were instances of tliis principle at work, as the 

 flowers became habituated to self-fertilisation, and were then 

 fully fertile. 



We have, then, in such cases an actual demonstration of 

 the first step of the changes induced by self-fertilisation 

 continiially enforced ; and thereby a witness to one cause of 

 the origin of certain, and indeed, a very large number 

 of species. It is the converse process to that of insect 

 fertilisation, which itself I take to be the vera causa of the 

 origin of intercrossing species. 



It is, perhaps, worthy of note that, while both the number 

 of stamens and the quantity of pollen are thus often much 

 reduced in some flowers the capsules of which produce many 

 seeds, yet in others which set but one, as Fumaria, or at 

 least but few seeds, the number of stamens may remain 

 unaltered. This seems to me to be an additional proof that 

 such flowers are degradations from forms originally adapted 

 to intercrossing when much more pollen was requisite. 

 Hence the present forms are retentions of former ancestral 

 conditions. The following cases will illustrate this : — 

 Scleranthus perennis £ind species of Medicago have ten stamens 

 and one seed ; Daphne Laureola has eight stamens and one 

 seed; Ghenopodium h.a,s five stamens and one seed; similarly 

 is it the case with the large orders Composifce and Graminece. 



The phenomenon called " contabescence " by Gartner* 

 would seem to have its rationale in this adaptation to self- 

 fertilisation in some cases, and to diclinism in others, though 

 there are other causes which may bring it about, when it is 

 a purely pathological phenomenon. 



Mr. Darwin observes, " The anthers are affected at a 

 very early period in the flower-bud, and remain in the same 

 state (with one recorded exception) during the life of the 

 * An. and PI. under Doni., ii., p. 165. 



