PREFACE. 



The first germ of the theory contained in this 

 little volume was originally set forth as an article 

 in the Conihill Magazine, and I have to thank the 

 courtesy of the Editor and Publishers of that 

 periodical for their kind permission to expand it 

 into its present far fuller form. 



I have been encouraged thus to give it shape in 

 a more permanent dress by the friendly appre- 

 ciation of the late Mr. Darwin, who wrote to me 

 as follows with regard to the central idea of my 

 original paper — the derivation of petals from flat- 

 tened and abortive stamens : — " Many years ago 

 I thought it highly probable that petals were in 

 all cases transformed stamens. I forget (except- 

 ing the water-lily) what made me think so ; but 

 I am sure that your evolutionary argument never 

 occurred to me, as it is too striking and too appa- 

 rently valid ever to be forgotten." It appeared to 

 me that if the idea so commended itself to Mr. 

 Darwin, it might also commend itself to other 



