56 



Heredity and Environment 



DEVELOPMENT OF PSYCHICAL PROCESSES IN ONTOGENY 



AND PHYLOGENY 



All Living Things, Including 

 Germ Cells and Embryos, 

 Show: 



i. Differential Sensitivity = 

 Different Responses to Stimuli 

 differing in Kind or Quantity. 



2. Reflexes, Tropisms = 

 Relatively Simple, Mechanical 



Responses. 



3. Organic Memory = 



Results of Previous Experience 

 registered in General Proto- 

 plasm. 



4. Adaptive Responses = 

 Results of Elimination of Useless 



Responses through Trial and 

 Error. 



5. Varied Responses = 

 Dependent upon Conflicting Stim- 

 uli and Physiological States. 



6. Identity = 



Continuity of Individual Organi- 

 zation. 



Mature Forms of Higher Ani- 

 mals Show : 



Special Senses and Sensations = 

 Differentiated out of General Senses 



and Sensations. 

 2. Instincts (Inherited), Habits 

 (Acquired) = 

 Complex Reflexes, involving 

 Nerve Centers. 

 3 Associative Memory = 



Results of Experience registered 

 in Nerve Centers and Associa- 

 tion Tracts. 



4. Intelligence, Reason = 

 Results of Trial and Error plus 



Associative Memory, i.e., Ex- 

 perience. 



5. Inhibition, Choice, Will = 

 Dependent upon Associative 



Memory, Intelligence, Reason. 



6. Consciousness = 



Continuity of Memory, Intelli- 

 gence, Reason, Will. 



B. FACTORS OF DEVELOPMENT 



These are some of the facts of development, — a very incom- 

 plete resume of some of the stages through which a human being 

 passes in the course of his development from the germ. What are 

 the factors of development? By what processes is it possible to 

 derive from a relatively simple germ cell the complexities of an 

 adult animal? How can mind and consciousness develop out of 

 the relatively simple psychical elements of the germ? These 

 are some of the great problems of development — one of the 

 greatest and most far-reaching themes which has ever occupied 

 the minds of men. 



