66 HEREDITY AND ENVIRONMENT 



perimental and scientific work. Indeed the 

 scientific method is the method of trial and 

 error, and finally trial and success the 

 method recommended by St. Paul to prove all 

 things and hold fast that which is good. 



In Paramecium the reflex type of behavior 

 is relatively complete; there is no associative 

 memory and no ability to learn by experience. 

 In the earthworm associative memory is but 

 slightly developed and the animal learns but 

 little by experience and can make no applica- 

 tion of past experiences to new conditions. In 

 the dog associative memory is well developed; 

 the animal learns by experience and can, to a 

 limited extent, apply such memory of past ex- 

 periences to new conditions. In adult man all 

 of these processes are fully developed and par- 

 ticularly the last, viz., the ability to reason. 

 But in his development the human individual 

 passes through the more primitive stages of 

 intelligence, represented by the lower animals 

 named; the germ cells and embryo represent 

 only the stages of reflex behavior, to these trial 

 and error and associative memory are added in 

 the infant and young child, and to these the 



