18 



16 ilr. C. Davwin on the Fertilization of Orchiih. 



he wa3 convinced tliat I was in error, and tliat tlie flowers 

 are fertilized by small insects entering the labellum througli 

 the large opening on tlio njipcr surface, and crawling out in- 

 one of the two small oritices close to either anther' and the 

 stigma. Accordingly I caught a very small bee wliich seemed 

 ot about the right size, namely the Andrena parvula (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 

 upiier large opening. The bee vainly endeavoured to crawl 

 out again the same way, but always fell backwards, owino- to 

 the margins being inflected. The labellum thus acts like one 

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

 so .1 to catch beetles and cockroaches in the London kitchens. 

 Uitimately 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 ao-ain 

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

 through one of the small orifices. I repeated the operation 

 tiv-e times, always with the same result. I tlien cut away the 

 labellum, so as to examine the stigma, and found it vA\ 

 smeared over with pollen. Delpino (Fecondazione &c. 1SG7, 

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

 c iscovered to act m the manner just described ; for he argued 

 tliat it an insect were to insert its proboscis, as I had supposed, 

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

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

 own pollen ; and in this he did not believe, from havino- 

 confidence m 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 flower or plant 

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

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

 (\ erh d A at. Ver. Jahrg. xxv. III. Folge, v. Bd. p. 1) we 

 actually know that Cypripedium calceolus in a state of nature 

 IS fertilized by two species oi Andrena, in the manner above 

 supposed. 



On 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 m my work, is strongly confirmed by Prof Gray's 

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

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

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

 this species alone the stigma is slightly concave and viscid' 

 Ur. Lrray adds that m most of the species the broad stigma 

 presents another remarkable peculiarity, " in being closely 



