274 Animal Intelligence 



The evolution of the intellectual and moral nature which 

 a higher animal really possesses from the sort of a nature 

 which the real activities of the protozoa manifest, is far 

 less difficult to explain. 



In so far as the higher animal is a collection of original 

 tendencies to respond to physical events without and within 

 the body, subject to modification by the laws of exercise 

 and effect and by these alone, and in so far as the protozoan 

 is already possessed of a well-defined repertory of responses 

 connected with physical events without and within the 

 body in substantially the manner of the higher animal's 

 original tendencies, the problems of the evolution of be- 

 havior are definite and in the way of solution. 



The previous sections gave reason for the belief that the 

 higher animals, including man, manifest no behavior 

 beyond expectation from the laws of instinct, exercise and 

 effect. The human mind was seen to do no more than 

 connect in accord with original bonds, use and disuse, and 

 the satisfaction and discomfort resulting to the neurones. 

 The work of Jennings has shown that the protozoa already 

 possess full-fledged instincts, homologous with the instincts 

 of man. They too may have specialized receptors, an 

 action-system with a well-defined repertory and a connect- 

 ing system or means of influencing the bonds between the 

 stimuli received and the motor reactions made. The dif- 

 ficulties of tracing the possible development of a super-man 

 from an infra-animal thus disappear. 



There is, of course, an abundance of bona fide difficulty 

 in discovering the unlearned behavior of each group of 

 animals and in tracing, throughout the animal series, 

 changes in the physical events to which animals are sensi- 

 tive so that to each a different response may be attached, 

 changes in the movements of which animals are capable, 



