304 BIOLOGICAL LECTURES. 



h. Origin and Nature of the Behavior in Taking Food. 



I. Some Intelligence Implied. Let us now return to the 

 question of the origin and nature of the behavior of Necturus 

 in capturing its food ; not, however, with the expectation of 

 reaching a complete solution, but rather in the hope of coming 

 nearer to the problem and to the guiding principles in dealing 

 with it. It is obvious, first of all, that automatism will not 

 suffice to account for the whole behavior. That there is 

 organic coordination of movements no one will dispute. But 

 these movements must be steered in the direction of the 

 object, and this orientation does not seem to be a purely 

 automatic arrangement. The dermal sensillae ("lateral-line" 

 organs) give the impressions which enable the animal to 

 steer its course ; but action and sense impression are evidently 

 not linked in a way to be independent of inhibitory influ- 

 ences. I assume that the creature is conscious, and that it 

 has a certain intelligent appreciation of the sense impressions 

 received. This is not saying that the young Necturus is a born 

 philosopher ; I assume nothing more than that it has already 

 learned by experience how to direct its movements. That does 

 not imply much, but certainly some, intelligence. I cannot 

 otherwise understand why the same stimulus should not always 

 evoke the same response under the same conditions. But we 

 see that there is hesitation about starting, and this hesitation 

 may be prolonged to any length, showing conclusively that 

 sensation and response are not so connected as to exclude 



skin. Its prey, since it lives in the dark and its eyes are mere vestiges, is located 

 entirely by its tactile organs. This is done with as great accuracy as could be 

 done with the best of eyes in the light, but only when the prey is in close prox- 

 imity to the head. Coarser vibrations in the water are not perceived or are 

 ignored, and apparently stationary objects are not perceived when the fish 

 approaches them. If a rod is held in the hand, the fish always perceives it when 

 within about half an inch of it, and backs water with its pectorals. If the head 

 of a fish is approached with a rod, the direction from whence it comes is always 

 perceived and the correct motion made to avoid it. This reaction is much more 

 intense in the more active young than in the adult. One young, about 10 mm. 

 long, determined with as great precision the direction from which a needle was 

 coming as any fish with perfect eyes could possibly have done. It reacted 

 properly to avoid the needle, and this without getting excited about it. 



