CHAPTER IV 

 PARASITISM v. SYMBIOSIS 



THE conclusion is unavoidable from all the foregoing that Para- 

 sitism presents an " immoral " relation, the " bad " and truly 

 " diabolical " feature of which consists precisely in the deadly 

 way in which it antagonises the " moral," or " spiritual " prin- 

 ciple of " live and let live." In his little work on Plant Life, 

 Professor J. B. Farmer, F.R.S., tells us that some of the non- 

 green plants show " an almost diabolical ingenuity of physio- 

 logical action, as, for example, when some of the parasites, by 

 emitting an attractive excretion, cause their victims to actually 

 grow towards them." 



This being the case, it is all the more curious that Biologists 

 fail to recognise that the principle of Parasitism differs toto 

 coelo from that of Symbiosis. Professor Farmer, for instance, 

 although conceding that Symbiosis may be a means whereby 

 different species of plants achieve mutual benefits, economic 

 and otherwise, and hinting even that it may be one of the 

 " secret " methods and processes by which progressive evolution 

 has been brought about, yet provides the following, almost 

 paradoxical, definition of Symbiosis : 



There are many other instances of remarkable associations of two or 

 more plants, in which each is in turn more or less parasitic on the other 

 or, at the least, lives on the waste products formed as the result of the 

 chemical life processes of its associate. Such an association is often spoken 

 of as symbiosis, but it is evident that the transition from symbiosis to parasit- 

 ism is only a matter of degree. (Italics mine.) 



This exposition is inadequate and misleading. It is putting 

 the " good " symbiotic on the same level with the " bad " para- 

 sitic principle, which is far from satisfactory. Surely if waste 

 products or, for that matter, any surplus products whatever 

 come to be exchanged between " associates," this does not 

 constitute a case of Parasitism, though there be otherwise in 

 Nature a frequent occurrence of the transition from Symbiosis 

 to Parasitism. Such an exchange, however crude at first, 

 forms, on the contrary, the most essential basis of the " good," 



