242 THE WONDER OF LIFE 



anecdotes of animal sagacity were collected with more 

 zeal than discretion. 



We may associate with the name of Romanes in particu- 

 lar the beginning of a more critical period. Though he was 

 not always sufficiently stern himself, he did important 

 work in sifting the data, and in trying to separate out 

 precise observation from the more or less unconscious 

 inferences with which the recorder so often interpenetrates 

 it. He drew the useful distinction between perceptual 

 inference (intelligence), where a conclusion is drawn from 

 concrete representations, and conceptual inference (reason), 

 where the syllogism involves general concepts ; and showed 

 that there was no evidence compelling us to credit animals 

 with more than the former. Considerable progress has 

 also rewarded the work of the experimental school, who 

 have studied the process of ' learning ', of forming associa- 

 tions, of profiting by experience, of experimenting in novel 

 situations, and so on. 



Association. It was a great step in evolution when 

 animals began to associate sensations together. We mean 

 by a sensation, physiologically, an impression made on the 

 nervous system by external stimulus, and psychologically, 

 an awareness (to some degree) of the external stimulus. 

 Let us refer briefly to some of the experimental work which 

 has been done in the study of the association of sensations. 

 There is, for instance, the work of Pavlov and his school 

 on the establishment of associations in the dog. It is well 

 known that a dog's mouth may water when it sees food ; 

 there is a reflex stimulation of the salivary glands, not 

 by direct contact with food, but circuitously by a visual 

 impression. When the food is put in the dog's mouth, 

 the salivation must follow ; when the stimulation is cir- 



