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 larve. 
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, Amphithe longimana, and compared the 
activities of the adult with those of the newly hatched young. 
Amphithe 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 
= 
3 
