ZOOLOGICAL SCIENCE 217 



modern natural history, further illustrates the change from 

 observation to experimentation. The earlier studies were, 

 almost without exception, observational in their nature, but a 

 point was reached where progress became impossible by the 

 continuance of observation alone. No one recognizes more 

 clearly than does the ecologist the difficulties which attend 

 the introduction of experimentation in field zoology. 

 Observation still constitutes the major method. In the 

 plant, which is rooted to its environment, experimental 

 investigation is less difficult, and hence the ecology of plants 

 has advanced beyond that of animals. Yet in spite of the 

 difficulties, no one doubts that here, as elsewhere, observa- 

 tion will be increasingly supplemented by experimentation. 



RELATION OF ZOOLOGY TO OTHER SCIENCES 



The adoption of this growing measure of experimentation 

 has had an important bearing upon zoology in its relation 

 to allied sciences. For one thing, many biological inter- 

 ests that were becoming divergent have become unified. 

 Toward the close of the nineteenth century it seemed that 

 such biological studies as those found in the works of Darwin 

 were becoming impossible, because of the appalling amount 

 of special knowledge in the fields of zoology and botany. 

 No man could longer presume to become a master of both 

 sciences. While this is increasingly true, we find to-day that 

 the investigation of general biological phenomena, such as 

 growth, regeneration, heredity, and the like, leads to the 

 study of animals and plants by the same investigator. The 

 botanist and the zoologist find themselves on common 

 ground when engaged in such investigations. A separation 

 which had seemed an inevitable but regrettable incident in 

 the advance of science has been at least postponed. 



Again, a closer union has been effected between the 

 biological and the physico-chemical sciences, through study 

 of the physico-chemical processes that occur in the bodies 



