EVOLUTIONAL PSYCHOLOGY 75 



existence of some definite principle capable of acting as a rudder 

 and compass to the accumulation of variations. He would, no 

 doubt, were he still alive, be one of the first to welcome the 

 principle of Symbiogenesis as capable of accomplishing such 

 direction of evolution, both physiological and psychological. 



Again, Psychologists consider that " perceptions " are the 

 result of " acquisitions." " There is every reason to suppose " 

 says Professor James Sully in his Outlines of Psychology, 

 " that this simple act of referring impressions to things or objects 

 in space is the result of a long process of acquisition or learning 

 by experience." 



Sensations are interpreted by an act of perception, or, in other 

 words, they are " worked up " as an element into that compound 

 mental state which is called a percept. 



There obtains in fact, as has sometimes been remarked, a 

 kind of mental " alchemy." This " alchemy " I affirm, is 

 intimately connected with " industry." I look upon mental 

 acquisitions as a kind of funded wealth, built up by mental 

 work and the capitalisation of its results. The legitimacy of the 

 "capitalisation" depends upon bio-economic and bio-moral 

 factors. 



The mind is said to grow by what it assimilates. I would 

 urge in this connection that the symbiotic relation with its need 

 of industrious habits rivets the attention of the mind upon 

 reciprocal activities and thereby tends to fix a corresponding 

 state of mind a socialised mind, as it were, which we have 

 already found to be the sine qua non of psychological progress. 

 There is nothing like symbiotic endeavour to feed the mind and to 

 regulate mental developments in a salutary and permanently 

 useful manner. 



It was shown in a previous chapter that a great deal of 

 prejudice Ijad yet to be got rid of as regards the best methods 

 of feeding plants, particularly if we wish to aid the real welfare 

 and evolution of the plants rather than merely exploit them for 

 our immediate purposes. In the past, anything seemed good 

 enough for the plant so long as it afforded stimulation for rich and 

 luxurious productions, irrespective of the ultimate interests of 

 the plant. " Was gut stinkt, dasgutduengt." Only recently it 

 has dawned upon us that a plant is, like ourselves, under delicate 

 laws of life and of health, and, further, that in its " assimilations," 

 as in ours, it is quality rather than quanti'ty that counts. This 



