Chap. III. CErHALANTHERA GEANDIFLOEA. 83 



out of seventeen flowers which were, examined one day^ 

 flye had their ridges gnawed, and on the next day, 

 seven out of nine other flowers were in this state. As 

 there was no appearance of slime, I do not believe 

 that they had been attacked by slugs; but whether 

 they had been gnawed by winged insects, which alone 

 would be efi'ectual for cross-fertilisation, I know not. 

 The ridges had a taste like that of the labellum of 

 certain VandesB, in which tribe (as we shall hereafter 

 see) this part of the flower is often gnawed by insects. 

 Cephalanthera is the only British Orchid, as far as I 

 have observed, which attracts insects, by thus offering 

 to them solid food. 



The early penetration of the stigma by a multitude 

 of pollen-tubes, which were traced far down the stigmatic 

 tissue, apparently gives us another case, like that of the 

 Bee Ophrys, of perpetual self-fertilisation. I was much 

 surprised at this fact, and asked myseK : Why does the 

 distal portion of the labellum open for a short period ? 

 what is the use of the great mass of pollen above and 

 below that layer of grains, the tubes of which alone 

 penetrate the upper edge of the stigma ? The stigma 

 has a large flat viscid surface ; and during several years 

 I have almost invariably found masses of pollen adher- 

 ing to its surface, and the friable pillars by some means 

 broken down. It occurred to me that, although the 

 flowers stand upright, and the pillars are well pro- 

 tected from the wind, yet that the pollen-masses might 

 ultimately topple over from their own weight, and so 

 fall on the stigma, thus completing the act of self-fer- 

 tilisation. Accordingly, I covered with a net a plant 

 having four buds, and examined the flowers as soon as 

 they had withered ; the broad stigmas of three of them 

 were perfectly free from pollen, but a little had fallen 

 on one corner of the fourth. With the exception of 



