50 'WHAT IS A SPECIES?' 



with almost unexampled brilliancy and promise. The 

 time which we give to Societies such as this time we 

 are sometimes apt to grudge is well spent. Here, and 

 in kindred communities, a ' man sharpeneth the counten- 

 ance of his friend,' and there is born of the influence 

 of mind upon mind, thought, not a mere resultant of 

 diverse forces, but a new creation. 



The scientific man who shuts himself away from his 

 fellow men, in the belief that he is thereby obtaining 

 conditions the most favourable for research, is grievously 

 mistaken. Man, scientific man perhaps more inevitably 

 than others, is a social animal, and the contrast between 

 the lives of Darwin and Burchell shows us that friendly 

 sympathy with our brother naturalists is an essential 

 element in successful and continued investigation. 



Insects, and especially Lepidoptera, pre-eminently fitted to 

 supply examples for a Discussion on Species. 



I do not suppose that it is necessary to justify a dis- 

 cussion of the term ' species ' as the subject of the 

 Anniversary Address to the Entomological Society of 

 London. The students of insect form and function hold 

 an exalted place among naturalists. The material of 

 their researches enables them, almost compels them, to 

 take the keenest and most active interest in broad ques- 

 tions affecting the history and course of life on our planet. 

 Naturalists engaged upon other groups may reasonably 

 inquire why insects, above all other animals, should be 

 so especially valuable for the elucidation of the larger 

 problems which deal, not only with the species of a single 

 group, but with every one of the innumerable and infinitely 

 varied forms, vegetable no less than animal, in which life 

 manifests itself. The answer is to be found in the large 

 number of offspring produced by each pair of insects, 

 and the rapidity with which the generations succeed each 

 other, many cycles being completed in a single year in 

 warm countries ; in the severity of the struggle for life 

 which prevents this remarkable rate of multiplication 

 from becoming the cause of any progressive increase 



