78 POPULAR SCIENCE MONTHLY 



fulness in the field of comparative psychology. For the first time in 

 the history of thought, we have both a scientific and a philosophic 

 public sentiment ripe for a serious attempt at a correlation in scientific 

 channels of mental and physical evolution and of mind and body in 

 the broader view. 



But how imperfectly are we able to enter into the inner life of 

 even the higher animals whose minds are most like our own ! And 

 yet, who knows how many of the powerful, though subconscious springs 

 of our own impulse and motive may lie concealed in inherited vestiges 

 of long- vanished and far more remote ancestral mental powers? Who 

 knows what may be the mental life of a catfish, whose barbels and 

 whole outer body surface are covered with organs of taste and whose 

 gustatory nerves and centers are the biggest in the brain, or of a 

 shark which has an elaborate system of sense organs (the lateral line 

 canals), totally unknown to our own experience, which reach the ex- 

 treme dimensions of the body and serve as a sort of intermediary appa- 

 ratus between the organs of touch and the labyrinth of the ear, which 

 is likewise highly developed, though the fish is apparently nearly or 

 quite deaf? 



The first task of comparative psychology, then, is to define as 

 accurately as we may with the imperfect means at command the sensori- 

 motor life of the whole range of lower organisms. And this task is 

 fortunately not only approachable, but intrinsically attractive to every 

 lover of nature. The study in field and laboratory of the sensory life 

 of animals, while not all of comparative psychology, is a necessary in- 

 troduction to its larger correlations and is receiving a rapidly increas- 

 ing attention by naturalists of all schools; for the development of a 

 true comparative psychology is, as we have seen, bound up with some 

 of the greatest of the current movements in both science and philosophy. 



