274 SYMBIOSIS 



of these plants . The odour of many orchids is strong and offensive, 

 and in this they are like the " plant-animal " Convoluta, the case 

 of which was considered in Symbiogenesis. It was there pointed 

 out that such offensive odour was indicative of an in-feeding 

 diathesis, and, further, that scavengers and beasts of prey are 

 generally attracted by the odours emanating from diseased 

 individuals. In-feeding habits, therefore, are not the means of 

 preventing infection or of supporting ideal partnerships. We 

 have seen good reason for regarding the orchids, which have 

 surrendered " pivotal " vegetable industry, whilst contracting 

 the habit of in-feeding, as partly diseased organisms. If, as a 

 result, they are liable to infection, this is in keeping with their 

 degeneration ; if, on the other hand, they have partly succeeded 

 in checking or controlling would-be parasitic fungi, this is to be 

 credited to the survival amongst them of at least some good sense, 

 dating back in its origin to ancestral Norm-Symbiosis and pro 

 tanto due to something the very opposite of parasitic or pathological 

 relations. 



In Prof. Bernard's view, what means of limiting the " infec- 

 tion " are possessed by the orchids, are due to the exercise of 

 " phagocytosis," which is " capable a lui seul d'assurer rimmunite 

 quand les cellules de passage ont laisse penetrer le mycelium." 



But, we are assured, that this is only part of the story, and : 



Dans tous les cas au contraire ou les jeunes Orchidees perissent rapi- 

 dement par suite d'une infestation, la phagocytose n'entre plus en scene, ou 

 ne joue du moins qu'un role efface. ... Si 1'on se bornait a comparer 

 ces deux categories de cas extremes, il pourrait sembler que la phagocytose 

 a un role preponderant pour assurer rimmunite. Mais entre le cas de 

 1'infestation benigne, bientot enrayee par la digestion des champignons 

 dans les phagocytes et le cas de 1'infestation rapidement mortelle avec 

 phagocytose insignificante, il y a le cas intermediate de la symbiose ou la 

 phagocytose s'exerce sans arreter la progression des champignons et ou 

 cependant les plantes ne succombent pas. 



All of which is merely a roundabout way of saying that 

 definite conditions of mutual tolerance and mutual forbearance 

 have to be fulfilled before we can have a case of genuine mutual 

 usefulness, such as constitutes Symbiosis. May we not assume 

 that the body makes changes in its general means of defence 

 according to different requirements and in accordance with the 

 nature of every new relation ? If Prof. Bernard had not confined 

 himself to the study of second-rate Symbiosis, he would have 

 discovered that Symbiosis is the alternative to " struggle for 



