Facts and Factors of Development 49 



There is every evidence that human beings arrive at intelli- 

 gence and reason by the same process, a process of many trials 

 and errors and a few trials and successes, a remembering of these 

 past experiences and an application of them to new conditions. A 

 baby grasps for things which are out of its reach, until it has 

 learned by experience to appreciate distances ; it tests all sorts of 

 pleasant and unpleasant things until it has learned to avoid the 

 latter and seek the former ; it experiments with its own body until 

 it has learned what it can do and what it can not do. Is not this 

 learning by experience akin to the same process in the dog and 

 more remotely to the trial and error of the earthworm or the 

 adaptive reflexes of Parameciuni ? Is not intelligence and reason 

 in all of us, and upon all subjects, based upon the same processes 

 of trial and error, memory of past experiences and application of 

 these to new conditions? Surely this is true in all experimental 

 and scientific work. Indeed the scientific method is the method of 

 trial and error, and finally trial and success the method recom- 

 mended by St. Paul to 'prove all things and hold fast that which 

 is good/ 



Learning by Experience. 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 associa- 

 tive memory is but slightly developed and the animal learns but 

 little by experience and can make no application of past ex- 

 periences 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 experiences to new 

 conditions. In adult man all of these processes are fully devel- 

 oped and particularly 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 appli- 



