INSTINCT 93 



same idea may be expressed by the use of "brand-new" 

 scientific terms which have never been soiled by theologians 

 and metaphysicians, but the need for a general term for 

 kinds of behavior commonly classed as instinctive would 

 still remain, and despite the efforts of a few comparative 

 psychologists, the word instinct will I think continue in 

 reputable use. 



Illustrations of instinct abound everywhere and a very 

 few will suffice. A flesh fly when first emerging from its 

 pupa case is very soon ready for performing the various 

 functions of its life. It guides itself accurately in flight, 

 and deftly escapes its would be captors by quick and appro- 

 priate movements. It is drawn by the sense of smell to 

 suitable objects for food. It avoids various kinds of injur- 

 ious stimuli. It recognizes out of a vast number of animate 

 objects the opposite sex of its own species. When ready 

 to deposit its eggs it selects, out of a great variety of materials 

 the proper substances to afford food for its future larvae. 

 Its acts are unguided by previous experiences; they are not 

 prompted by reflection or thought; they result from a blind 

 impulse urging the insect to discharge its energies in certain 

 specific ways without knowing why. An organism of the 

 degree of psychic development of a flesh fly may modify its 

 acts to a certain degree through the effects of experience, 

 but as a matter of fact such modification plays but a small 

 part in the creature's life. 



Some years ago the writer studied the behavior of a species 

 of amphipod, Amphithce longimana, and compared the 

 activities of the adult with those of the newly hatched young. 

 Amphithce lives in tubular nests which are usually lodged 

 among sea weed. The nests are somewhat longer than the 

 animal and are spun of a web-like material into which bits 

 of sea weed are often incorporated which help to conceal 



