August 29, 1913] 



SCIENCE 



287 



tion recapitulates the experience of the 

 species and of the individual — awakens the 

 phylogenetic and ontogenetic memory. In 

 other words, sights, sounds and odors are 

 symbols which awaken phylogenetic asso- 

 ciation. If a species has become adapted 

 to make a specific response to a certain 

 object, then that response will occur auto- 

 matically in an individual of that species 

 when he hears, sees or smells that object. 

 Suppose for example, that the shadow of a 

 hawk falls simultaneously on the eyes of a 

 bird, a rabbit, a cow and a boy. That 

 shadow would at once activate the rabbit 

 and the bird to an endeavor to escape, each 

 in a specific manner according to its phylo- 

 genetic adaptation; the cow would be in- 

 different and neutral; while the boy, ac- 

 cording to his personal experience or on- 

 togeny, might remain neutral, might watch 

 the flight of the hawk with interest or 

 might try to shoot it. 



Each phylogenetic and each ontogenetic 

 experience develops its own mechanism of 

 adaptation in the brain; and the brain 

 threshold is raised or lowered to stimuli by 

 the strength and frequency of repetition 

 of the experience. Thus through the in- 

 numerable symbols supplied by environ- 

 ment the distance ceptors drive this or that 

 animal according to the type of brain pat- 

 tern and the particular state of threshold 

 which has been developed in that animal 

 by its phylogenetic and ontogenetic experi- 

 ences. The brain pattern depends upon 

 his phylogeny, the state of threshold upon 

 his ontogeny. Each irain pattern is cre- 

 ated by some particular element in the 

 environment to which an adaptation has 

 been made for the good of the species. 

 The state of threshold depends upon the 

 effect made upon the individual by his 

 personal contacts with that particular ele- 

 ment in his environment. The presence of 

 that element produces in the individual an 



associative recall of the adaptation of his 

 species — that is, the brain pattern devel- 

 oped by his phylogeny becomes energized 

 to make a specific response. The intensity 

 of the response depends upon the state of 

 threshold — that is, upon the associative 

 recall of the individual's own experience — 

 his ontogeny. 



If the full history of the species and of 

 the individual could be known in every 

 detail, then every detail of that individ- 

 ual's conduct in health and disease could 

 be predicted. Eeaction to environment is 

 the basis of conduct, of moral standards, of 

 manners and conventions, of work and 

 play, of love and hate, of protection and 

 murder, of governing and being governed, 

 in fact, of all the reactions between human 

 beings — of the entire web of life. To quote 

 Sherrington once more : ' ' Environment 

 drives the brain, the brain drives the vari- 

 ous organs of the body." 



By what means are these adaptations 

 made; what is the mechanism through 

 which adequate responses are made to the 

 stimuli received by the ceptors? We pos- 

 tulate that in the brain there are innumer- 

 able patterns each the mechanism for the 

 performance of a single kind of action, and 

 that the brain cells supply the energy — 

 electric or otherwise — by which the act is 

 performed; that the energy stored in the 

 brain cells is in some unknown manner re- 

 leased by the force which activates the 

 brain pattern; and that through an un- 

 known property of these brain patterns 

 each stimulus causes such a change that 

 the next stimulus of the same kind passes 

 with greater facility. 



Each separate motor action presumably 

 has its own mechanism — brain pattern — 

 which is activated by but one ceptor and 

 by that ceptor only when physical force of 

 a certain intensity and rate of motion is 

 applied. This is true both of the visible 



