BUTTERFLY PSYCHOLOGY. 151 



it in all its movements. In like manner, and 

 by a like mechanism, the female butterfly or 

 moth selects the right spot for laying her 

 eggs, which of course depends entirely upon 

 the nature of the young caterpillars' proper 

 food. Each great group of insects has its 

 own habits in this respect, may-flies laying 

 their eggs on the water, many beetles on 

 wood, flies on decaying animal matter, and 

 butterflies mostly on special plants. Thus 

 throughout its whole life the butterfly's ac- 

 tivity is entirely governed by a rigid law, 

 registered and fixed for ever in the con- 

 stitution of its ganglia and motor nerves. 

 Certain definite objects outside it invariably 

 produce certain definite movements on the 

 insect's part. No doubt it is vaguely con- 

 scious of all that it does : no doubt it derives 

 a faint pleasure from due exercise of all its 

 vital functions, and a faint pain when they 

 are injured or thwarted ; but on the whole 

 its range of action is narrowed and bounded 

 by its hereditary instincts and their nervous 



