28o SYMBIOSIS 



a self-sufficiency which, though not prejudicial to numbers, is 

 yet detrimental to the ultimate well-being of the species. For, 

 as already mentioned, the plant presents a dimorphism an 

 antagonism between a condition of cross-fertilisation and one of 

 self-fertilisation, so much so as to cause Darwin to exclaim that the 

 case is " perplexing in an unparalleled degree." 



And perplexing the case of the Fly Orchis certainly is, unless 

 we attribute the dualism of contrivances to a double state of 

 biological relation one a state of lingering Norm-Symbiosis, 

 and another, conflicting with and detracting from it : a state of 

 Luxury-Symbiosis ; the dualism in the last analysis presenting 

 an antithesis between a cross-feeding and an in-feeding state. 



By way of contrast with the above cases, we might mention 

 an orchid emitting " a strong hone3'-like odour, such as Herminium 

 monorchis, the Musk Orchis ; and here we find that although the 

 flowers are small and inconspicuous, yet " they seem highly 

 attractive to insects " de toute taille bon chien. 



Darwin's son, George, brought home no less than twenty-seven 

 specimens of minute insects with pollinia attached to them. 

 These insects belong to Hymenoptera, Dipt era and Coleoptera. 



So with Gymnadenia Conopsea : 



the flowers smell sweet, and the abundant nectar always contained in their 

 nectaries seems highly attractive to Lepidoptera, for the pollinia are soon 

 and effectually removed. 



We may take it that these sweet-scented orchids are little 

 given to in-feeding, and that, hence, they are not extremely 

 determined by the fungi. 



If we come to the Arethuseae, an interesting example is presented 

 by Cephalanthera Grandiflora, which, as Darwin says, is like a 

 degraded Epipactis, a member of the Neotteae. Darwin never 

 found a trace of nectar within the cup of the labellum. Yet, 

 as there is evidence of insect visits, Darwin's search brought to 

 light the fact that there are insects which gnaw the ridges of the 

 flowers, and he says : 



The ridges had a taste like that of the labellum of certain Vandeae 

 in which tribe this part of the flower is often gnawed by insects. Cephalan- 

 thera is the only British Orchid, as far as I have observed, which attracts 

 insects, by thus offering to them solid food. 



Here, as in the case of the Bee Orchis, we have self-fertilisa- 

 tion. It seems, therefore, that insects of some kind visit the 

 flowers, disturb the pollen, and leave masses of it on the stigmas 



