80 SYMBIOSIS 



for drilling organisms into habits and eliminating those which 

 cannot learn." 



We might ask this : Who are those " which cannot learn ? " 

 Are they such as have never " learnt," whose ancestors had never 

 " learnt ? " Or have they at one time or another stopped 

 " learning," thus coming through disobedience to a sociological 

 and quasi-moral law, under the penalty of elimination ? Thanks 

 to Bio-Economics, we can now say with a clear conscience that 

 evolution is a process for drilling organisms into " good " habits 

 and disqualifying and penalising those which, in disobedience 

 to the bio-moral trend of things, nevertheless allow themselves 

 to lapse into " bad " habits. " Learning " depends upon the 

 power of profiting by, and storing up the results of, experience ; 

 on the power of forming " perceptions " of some kind ; all of 

 which in turn depends upon the " working up of sensations," 

 the pre-requisite throughout being : definite, moderate, and 

 systematic activities of the nature of industries, and a faithful 

 maintenance of wholesome activities. All of which, again, requires 

 definite economic and biological associations of a permanent 

 character, which, as we have seen, only widely useful organisms 

 can afford to entertain. 



Our assumption that the plant plays an important role in 

 the evolution of mind, gains in strength with every fresh dis- 

 covery of substances potent in animal life and co-evolved by 

 the plant in the course of co-operative evolution. Such dis- 

 coveries are multiplying fast and coming to the front, similarly 

 to the way in which the importance of the biological as the 

 chief causative factor in evolution generally may be said to have 

 come into prominence. There can no longer be any doubt 

 that a wholesale re-interpretation of Biology is rendered necessary 

 by the discovery, for instance, of such important symbiotic 

 agents as the body-defending Phagocytes, of the agriculture- 

 sustaining, nitrifying Bacteria, of the " disinfectant " micro- 

 organisms, of the indispensable, life-giving Vitamines all anti- 

 thetic in action to the non-symbiotic or pathogenic micro- 

 organisms, or to the death-dealing alkaloid substances, for 

 instance. The number of " deficiency diseases," due to the 

 absence of Vitamines in the diet, is seen to be greater than at 

 first thought. Says Dr. F. M. Sandwich in the Lancet (23rd 

 October, 1915) : " Slowly and laboriously, we have learnt that 

 under the essential needs of an animal's diet are organic 



