Heredity and Environment 



DEVELOPMENT OF PSYCHICAL PROCESSES IN ONTOGENY AND PHYLOGENY OUT 



OF GENERAL IRRITABILITY OR SENSITIVITY CAPACITY 



OF RESPONDING TO STIMULI 



ALL LIVING THINGS, INCLUDING 

 GERM CELLS AND EMBRYOS, 

 SHOW: 



1. 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. 



7. Subjective Phenomena, if any, 

 Accompanying preceding pro- 

 cesses. 



MATURE FORMS OF HIGHER ANI- 

 MALS SHOW: 



i. 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. 



7. Feelings, Emotions 

 Accompanying one or more of pre- 

 ceding processes. 



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 



