66 SYMBIOSIS 



Let us recall, as an apt illustration, the case of the lichen. 

 Here we have a relation, primarily economic, namely, a 

 systematic co-operation between organisms of different species, 

 resulting in such mutual stimulation and mutual enhancement 

 as to produce a new and stable relation, and in general such 

 fortification of the protoplasm as to lead to considerable per- 

 manence, to considerable degrees of bio-economic and general 

 effectiveness and success of the compound organism. 



The manner in which alga and fungus have here compounded 

 their sexual relations following in the wake of economic partner- 

 ship, and coupled with non-predaceous ways of feeding, is symp- 

 tomatic of the way in which a desirable and lasting intimacy 

 together with genuine evolutionary progress are normally 

 achieved. What it brings out is this : Permanence is contingent 

 upon right sociological and bio-economic conduct. Given this 

 conduct, it is not a long step to the establishment of equitable 

 and lastingly beneficent sexual relations with subsequent 

 acceleration in the development of Sympathy. 



The progressive evolution of Sex itself, broadly viewed, 

 provides another illustration of the same truth. The duty of 

 Sex, like that of mind, is, at any rate at the higher stages of life, 

 generally deputed to a special organ which nevertheless depends 

 for its perfect working on the fullest co-operation it can obtain 

 from the other parts of the body. This inner co-operation, 

 or internal Symbiosis, depends, as we have seen, in turn, in an 

 important manner, on the external, i.e., " biological," Symbiosis 

 entertained by the respective species with others. The evolution 

 of Sex may, therefore, be justly viewed as due to the perfection 

 and expansion of Symbiosis. The mammalia, the most developed 

 partners of the plant to whom they owe an enormous debt 

 are also the most advanced as regards harmony and perfection 

 of the sexual life and equally as regards mentality and feeling. 

 Here too we have a case of permanence of domestic and bio- 

 logical relations, of mutual forbearance and righteous biological 

 conduct. Man, the most developed mammal, may be said to 

 owe his status largely to the fact that he is essentially a symbiotic 

 cross-feeder and thereby most fitted for permanent reciprocal 

 relations with the higher plants. 



More than one Zoologist has expressed wonderment at the 

 astounding number of mammalia that feed more or less exclu- 

 sively on plant products. And these mainly cross-feeding 



