156 Mr. C. Darwin on the, Ffrtilization of Orch{(l<^. 



he was convinced that I was in error, and that the flowers 

 are fertilized by small insects entering the labellum through 

 the large opening on the upper surface, and crawling out by 

 one of the two small orifices close to either anther and the 

 stigma. Accordingly I caught a very small bee which seemed 

 of about the right size, namely the Andrena ^arvula (and this 

 by a strange chance proved, as we shall presently see, to be 

 the right genus), and placed it in the labellum through the 

 upper large opening. The bee vainly endeavoured to crawl 

 out again the same way, but always fell baclcAvards, owing to 

 the margins being inflected. The labellum thus acts like one 

 of those conical traps with the edges turned inwards, which are 

 sold to catch beetles and cockroaches in the London kitchens. 

 Ultimately the little bee forced its way out through one of the 

 small orifices close to one of the anthers, and was found when 

 caught to be smeared with the glutinous pollen. I then again 

 put the same bee into the labellum ; and again it crawled out 

 through one of the small orifices. I repeated the operation 

 five times, always with the same result. I then cut away the 

 labellum, so as to examine the stigma, and found it well 

 smeared over with pollen. Delpino (Fecondazione &c. 1867, 

 p. 20) Avith much sagacity foresaw that some insect would be 

 discovered to act in the manner just described ; for he argued 

 that if an insect were to insert its proboscis, as I had supposed, 

 from the outside through one of the small orifices close to one 

 of the anthers, the stigma would be fertilized by the plant's 

 own pollen 5 and in this he did not believe, from having 

 confidence in what I have often insisted on — namely, that all 

 the contrivances for fertilization are arranged so that the 

 stigma shall receive pollen from a distinct floAver or plant. 

 But these speculations are now all superfluous ; for, owing to 

 the admirable observations of Dr. H. Miiller, of Lippstadt 

 (Verb. d. Nat. Ver. Jahrg. xxv. III. Folge, v. Bd, p. 1), we 

 actually know that Cypripedium calceohts in a state of nature 

 is fertilized by two species of Andrena, in the manner above 

 supposed. 



0)1 the relation between the more or less viscid condition of 

 the pollen and stigma in Cypripedium (p. 276). — The relation 

 between the state of the pollen and stigma, which I have 

 pointed out in my work, is strongly confirmed by Prof. Gray's 

 statement (Amcr. Journ. of Science, vol. xxxiv. 1862, p. 428), 

 namely, that in C. acaule the pollen is much more granular or 

 less viscid than in other American species of the genus, and in 

 this species alone the stigma is slightly concave and viscid ! 

 Dr. Gray adds that in most of the species the broad stigma 

 presents another remarkable ])eculiarity, " in being closely 



