28O FERTILISATION [lS66. 



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 ' Jahrbucher,' vol. v. The 

 memoir on Salvia alluded to is contained in the previous 

 volume of the same Journal :] 



C. Darwin to F. Hildebrand* 



Down, May 16 [1866]. 



MY DEAR SIR, The state of my health prevents my attend- 

 ing 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 observa- 

 tions 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- 

 vidual plants of Lobelia, &c., described by Gartner, and of 

 Passiflora and Orchids described by Mr. Scott. . . . 



Since writing to you before, I have read your admirable 

 memoir on Salvia, and it has interested me almost as much as 

 when I first investigated the structure of Orchids. Your 

 paper illustrates several points in my ' Origin of Species," 

 especially the transition of organs. Knowing only two or 

 three species in the genus, I had often marvelled how one 

 cell of the anther could have been transformed into the mov- 

 able plate or spoon ; and how well you show the gradations ; 



* Professor of Botany at Freiburg. 



