70 Dr W. Eutherford on the Fertilisation of Oi-chids. 



example — the pollinia are removed only when the insect 

 retires from the flower. 



Sprengel, in 1795, and Eobert Brown, in 1833, though 

 the latter was not without his doubts on the subject, both 

 expressed their belief in the necessity for insect agency ; 

 and many others have concurred with the opinion ; but 

 Darwin was the first to show that the necessity for insects, 

 which was previously considered to be confined to a few, is 

 almost universal. My observations, so far -as they have ex- 

 tended, have most thoroughly convinced me of the truth of 

 Mr Darwin's statement. But I must here mention, to 

 prevent any misunderstanding, that I have examined four 

 species only, — for the district in which I resided contained 

 only these four species, although they were severally repre- 

 sented by large numbers of individuals, so that I was able 

 to make a pretty thorough examination of each species. I 

 was staying in a part of Kent where Orchis maculata and 

 Cephalanthera grandiflora were especially abundant ; and 

 Gymnadenia conopsea, and Orchis jpyramidalis, to a lesser 

 degree. I examined 1175 fiowers of Cephalanthera^ 1000 of 

 Orchis maculata, 244 of Gymnadenia conop>sea, and 60 of 

 Orchis pyramidalis, in all 2479 flowers. This number may 

 seem very large ; but it must be remembered, that the fiowers 

 grew abundantly in the locality ; and I had but little diffi- 

 culty in procuring them. All the plants grew near, or in, 

 woods, so that they were most favourably situated for visi- 

 tation by insects. Mr Darwin says, that on one occasion 

 only has he seen an insect capable of carrying away the pol- 

 linia visit an Orchis. I have been more fortunate ; for I 

 have repeatedly observed, especially on warm, cloudy days, 

 lepidopterous insects paying their visits ; and on one occa- 

 sion I actually saw an insect remove the pollinia. Al- 

 though Mr Darwin thinks that an insect does not confine its 

 visitations to one particular species, but embraces several, — 

 an opinion which he has shown to be true in the case of 

 some one or two insects, — I must say that Orchis maculata 

 and Cephalanthera grandiflora, although growing together, 

 were visited by totally distinct insects, and either species 

 was only visited by one kind of insect. 



This fact is certain regarding the fertilisation of three 



