Aquatic Hitt 



165 



slower vibratory movements we, with all 

 our boasted brain power, must admit 

 ourselves inferior to the fishes. They 

 possess an elaborate system of cutaneous 

 and subcutaneous sense organs of which 

 we have not a vestige. These so-called 

 lateral line organs in the catfish com- 

 prise a complex system of fine tubes un- 

 der the skin, the lateral line canals, and 

 two kinds of sense organs in the sk'n, 

 the pit organs. The canals ramify in 

 various directions in the head and trie 

 main lateral canal extends along the 

 side of the body back to the tail. They 

 were formerly supposed to be for the 

 secretion of mucus and are still often 

 called the mucous canals. But they are 

 now known to contain numerous small 

 sense organs which respond to slow vi- 

 bratory movements of the water. The 

 pit organs are scattered over the skin, 

 the smaller ones each in a flask-shaped 

 pit with a narrow mouth and the less 

 numerous larger ones exposed on the 

 surface. 



The lateral line sense organs are all 

 supplied by a single system of nerves 

 related to the nerves of the ear, and quite 

 distinct from those for the general tac- 

 tile and chemical senses of the skin and 

 cutaneous taste buds. That the lateral 

 line organs .respond to slow vibratory 

 movements has been clearly shown by 

 Parker, but the distinctive features of the 

 pit organs are unknown and, in fact, our 

 knowledge of the functions of the sys- 

 tem as a whole is still very incomplete. 



It is clear that cutaneous organs of 

 touch, lateral line organs, and the organs 

 of equilibrium and hearing in the inter- 

 nal ear form a graded series, and all have 

 probably been derived in evolution from 

 a primitive type of tactile organ. When 

 therefore we both hear and feel a musical 

 tone of the piano we are reminded of the 

 long and dramatic history of the very 

 intricate human auditory organ, whose 



first and last stages both may function 

 at the same time in our own bodies. 



We cannot here recount the details of 

 the long series of very tedious scientific 

 investigations required to replace the 

 conjectures of amateur naturalists and 

 fisherfolk by accurate knowledge of the 

 sensory life of fishes. And even with this 

 precise information we are far from a 

 true understanding of the fishes' minds. 

 To learn the structure and behavior of 

 any animal requires only sufficient 

 scientific skill and industry, but to under- 

 stand the mind of an animal is the most 

 baffling of all scientific questions. 



Our own thoughts are purely personal 

 matters. Even with the aid of language, 

 facial expression and gesture, we are able 

 to communicate our ideas and feelings 

 to our intimate friends only imperfectly, 

 and this difficulty is multiplied many fold 

 when we try to understand even the most 

 intelligent of the brutes. The only re- 

 course is to see how an animal behaves 

 in a given situation and then in the light 

 of what we know of human and animal 

 bodily structure and function try to im- 

 agine how we would think in such a 

 situation, taking into account the animal's 

 limitations of nervous organization. Ob- 

 viously this is a poor and uncertain 

 method at best, and no wonder many 

 psychologists have given up the prob- 

 lem in despair and decided that the only 

 scientific procedure is to pay no attention 

 to animals' minds and limit our inquiry 

 to their objective behavior. Indeed, so 

 impressed are some of them by the fu- 

 tility of scientific study of even the hu- 

 man mind by introspection that they 

 advocate throwing overboard the whole 

 science of psychology. But this is too 

 like sinking the ship, cargo and all, to 

 get rid of the rats. 



No, if we wish to attain the heights of 

 a true understanding of the significance 



