2 7 o POPULAR SCIENCE MONTHLY 



that which serves as food. In other words the animal responds pri- 

 marily to water undulations, regardless of their cause, because it is 

 through such undulations that it receives notice of the presence of 

 food. In its most typical form instinct is thus seen to be chiefly a 

 matter of animal organization, and the response to stimuli to be 

 largely mechanical. This makes stable conditions necessary if it is 

 to meet educational needs. But even here there is a little variation 

 in the manner of reaction. Necturus has learned to discriminate some- 

 what between experiences, for, according to Whitman, " there is unmis- 

 takably a power of inhibition strong enough to counteract the strongest 

 motive to act — the hunger of a starving animal in the presence of 

 food." 4 But such limited power of reaction does not go far, and it 

 will meet the needs of animals only so long as their life is of the 

 simplest sort. They are probably capable of few adaptations, and these 

 must be made at an enormous cost of time and life. But as life be- 

 comes more complex and less regular these instinctive responses do not 

 answer. Animals must now learn to remember, and their actions must 

 be guided by past experiences of threatening disaster, else they can 

 not survive in the struggle. 



Not many experiments have been made on the educability of 

 animals low in the scale, but fishes have been taught to refrain from 

 attacking minnows that are their usual food, by separating them with 

 a glass partition extending across the aquarium until the larger fishes 

 learn by repeated bumps on the nose that the little ones are not to be 

 eaten. 5 Thorndike 6 has shown also that the minnow, Fundulus, can 

 learn to find its way through a series of three partitions, each with an 

 opening so located as to make the journey circuitous, and that it gradu- 

 ally improves on its previous record by eliminating blunders until 

 finally it learns to go directly to each opening. While we do not 

 know much about the mental processes here, it grows increasingly 

 harder to explain action solely by the neural mechanism. Experience 

 is evidently taking a more active part in the animal's life. The nervous 

 system is becoming more flexible, more adaptable. 



Recent observation has somewhat modified our views regarding 

 action among lower animals. Jennings's studies 7 indicate that the 

 method of trial and error is common even in one-celled organisms. 

 This method, wherever found, unquestionably involves in some degree 

 the utilization of experience. Such creatures can no longer be con- 

 sidered as merely reflex organisms in the presence of new needs and 



* hoc. cit., p. 305. 



5 See statement of Moebius's experiment in Darwin's "Descent of Man," 

 second edition, p. 76, and Triplett's "The Educability of the Perch," Am. 

 Journal of Psychology, Vol. 12, p. 354. 



"Am. Naturalist, Vol. 33, p. 923. 



7 " Contributions to the Study of the Behavior of Lower Organisms," p. 237 ; 

 Carnegie Institution, Washington, 1904. '* Behavior of Lower Organisms," 1906. 



