0>/V*) cvO'^VT) (tO^,^T> (Vs>'C^ ctO/C-^ tN^^^^ (vO<W) cvO^>f) (V<^''>f) rvO'^/r cT<^'r^ 



INTRODUCTION 



MAN is today the central figure in the living world. 

 Therefore the study of the life about us must 

 be approached through the application of 

 the human yardstick. First of all we must appraise 

 the living world in terms of its direct relationship to 

 man. Beginning with the known — ourselves — we 

 may measure the nearer portions of the unknown; and 

 not till this is done may we with any confidence take 

 up the broader problems of the world of animals 

 and plants. 



But the human yardstick has its limitations. To a 

 very large extent we are detached from the world in 

 which we live. Our environment we modify to suit 

 ourselves. We are therefore quite unfamiliar with 

 the terrible realities of existence that must be faced 

 by all other living things — that were faced also by 

 our ancestors. 



So overwhelming are the odds against all living 

 things, so precarious is the existence of any indi- 

 vidual, that it is not practicable to discuss the varied 

 contacts of all forms of life from the human aspect. 

 Yet an appreciation of these contacts is essential to 

 an understanding of the living world. In order to 

 overcome this difficulty we shall present this subject 

 in terms of its relation to the life of a butterfly. From 

 the infinity of different contacts which we find in our 

 contemplation of a butterfly we shall select a few for 

 more detailed exposition. 



[xi] 



