BY-PATHS OF BIOLOGY. 253 



and others partially erroneous, and that he often builds 

 a vast superstructure on a very uncertain basis of 

 doubtfully interpreted facts. Now, even admitting this 

 criticism to be well founded and I myself believe that 

 to a limited extent it is so I nevertheless maintain that 

 Darwin is not and cannot be too highly rated ; for his 

 greatness does not at all depend upon his being in- 

 fallible, but on his having developed, with rare patience 

 and judgment, a new system of observation and study, 

 guided by certain general principles which are almost as 

 simple as gravitation and as wide-reaching in their 

 effects. And if other principles should hereafter be 

 discovered, or if it be proved that some of his subsidiary 

 theories are wholly or partially erroneous, this very 

 discovery can only be made by following in Darwin's 

 steps, by adopting the method of research which he has 

 taught us, and by largely using the rich stores of 

 material which he has collected. The Origin of Species, 

 and the grand series of works which have succeeded it, 

 have revolutionized the study of biology ; they have 

 given us new ideas and fertile principles ; they have 

 infused life and vigour into our science, and have opened 

 up hitherto unthought-of lines of research on which 

 hundreds of eager students are now labouring. What- 

 ever modifications some of his theories may require, 

 Darwin must none the less be looked up to as the 

 founder of philosophical biology. 



As a small contribution to this great subject, I propose 

 now to call your attention to some curious relations of 

 organisms to their environment, which seem to me 

 worthy of more systematic study than has hitherto been 

 given them. The points I shall more especially deal 



