4 54 FERTILISATION OF FLOWERS. [1S66. 



Passiflora princeps struck me at the time as very remark- 

 able." 



With regard to the spread of a belief in the adaptation of 

 flowers for cross-fertilisation, my father wrote to Mr. Ben- 

 tham April 22, 1868 : 



" Most of the criticisms which I sometimes meet with in 

 French works against the frequency of crossing, I am certain 

 are the result of mere ignorance. I have never hitherto 

 found the rule to fail that when an author describes the 

 structure of a flower as specially adapted for self-fertilisation, 

 it is really adapted for crossing. The Fumariacese offer a 

 good instance of this, and Treviranus threw this order in my 

 teeth ; but in Corydalis, Hildebrand shows how utterly false 

 the idea of self-fertilisation is. This author's paper on Salvia 

 is really worth reading, and I have observed some species, 

 and know that he is accurate." 



The next letter refers to Professor Hildebrand's paper on 

 Corydalis, published in the ' Proc. Internat. Hort. Congress,' 

 London, 1866, and in Pringsheim's ' Jahrbiicher,' vol. v. The 

 memoir on Salvia alluded to is contained in the previous vol- 

 ume of the same Journal :] 



C. Darwin to F. Hildebrand* 



Down, May 16 [1866]. 

 My dear Sir, — The state of my health prevents my at- 

 tending the Hort. Congress ; but I forwarded yesterday your 

 paper to the secretary, and if they are not overwhelmed with 

 papers, yours will be gladly received. I have made many 

 observations on the Fumariaceae, and convinced myself that 

 they were adapted for insect agency ; but I never observed 

 anything nearly so curious as your most interesting facts. I 

 hope you will repeat your experiments on the Corydalis on a 

 larger scale, and especially on several distinct plants ; for your 

 plant might have been individually peculiar, like certain indi- 



* Professor of Botany at Freiburg. 



