EVOLUTIONAL PSYCHOLOGY 81 



substances, so small in amount that they may be easily over- 

 looked by the chemist and wholly unsuspected by the physician." 

 The plant alone possesses the secret of the manufacture of 

 Vitamines. A vast amount of the right kind of experience 

 and of the right kind of " learning " must have preceded the due 

 establishment of the plant's subtle bio-chemical and psycho- 

 genetic powers. 



