14 



NATURALIST'S GUIDE TO THE AMERICAS 



to habitat relations. An adequate in- 

 terpretation of evolutionary relations 

 can hardly be made without knowledge 

 of environment. This is true even if 

 natural selection operating on charac- 

 ters which arise from internal causes, 

 is assumed to be the only cause of the 

 origin of new forms. The geneticists 

 have rarely separated environmental 

 effects from purely hereditary phenom- 

 ena. It is safe to assume that a 

 considerable part of the phenomena 

 described as hereditary is some form of 

 environmental effect. The results of 

 genetical study can hardly have impor- 

 tant evolutionary bearing until rela- 

 tions to environment have been brought 

 into it. 



The relations of physiology to ecology 

 are more intimate under present condi- 

 tions; the general physiologists are inter- 

 ested in and are appreciative of ecological 

 work. The interpretation of physiolog- 

 ical characters in connection with en- 

 vironmental relations is a growing field. 

 Medical physiology is less intimately 

 related to environmental subjects but is 

 far from as remote as the present status 

 of various other biological subjects. 



The purpose of pointing out the rela- 

 tions of the various branches of biology 

 to ecology and the study of natural 

 habitats, and of calling attention to 

 neglected relations is merely to indi- 

 cate that present interest in the pres- 

 ervation of natural habitats for scien- 

 tific purposes is far less than it may be 

 expected to be in the near future. It 

 is safe to predict that when the neglected 

 field of habitat relations comes to 

 attention a little more, not merely 

 ecologists, but all biologists will re- 

 quire preserves of natural conditions 

 in connection with their various scien- 

 tific interests. The relations of the pure 



science of biology to natural conditions 

 is believed to be much more important 

 to future research than is generally 

 recognized. 



Agricultural problems include the 

 development of new kinds of cultivated 

 plants and domestic animals, and the 

 destruction of pests of all kinds. In 

 understanding conditions which most 

 favor pests a knowledge of their original 

 habitat is often very important and 

 will save years of work on the part of 

 investigators. For example the chinch 

 bug was originally found on grasses 

 in waste places along the coast of the 

 Carolinas. Rainy, hot seasons similar 

 to those found in the original area are 

 favorable to the chinch bug. Knowl- 

 edge of the climate and other condi- 

 tions in the original habitat would 

 have saved much useless speculation 

 and misinterpretation. Knowledge of 

 the original conditions under which a 

 pest lives is usually important. Ac- 

 cordingly preserves of natural conditions 

 are important from the standpoint of 

 insect pests and equally important for 

 other plant and animal pests. 



Domestic animals, especially sheep, 

 have been studied in relation to climate. 

 After thousands of years of domestica- 

 tion sheep still require conditions simi- 

 lar to those in which they are said to 

 have originally occurred mountain 

 grassland and failure to supply these 

 conditions is one of the causes of diffi- 

 culty in the sheep industry. A reserva- 

 tion with sheep of the wild sort in their 

 natural conditions would have facili- 

 tated this study greatly. There are 

 many species now in a wild state which 

 may be utilized in the near future for 

 domestication or crossing with domestic 

 species and they should be preserved 

 in their native haunts for this purpose. 



