250 



Biology in America 



I know, substantiated by any other investigator, and his own, 

 more reeent work in California has strikingly failed to sup- 

 port his previous experiments. In his later work Sumner 

 has been studying the relatioji between climate and color of 

 several races of California deer mice (Peromyscus). The 

 climate of California presents all possible gradations, from the 

 arctic conditions of the Sierra summits to the torrid heat of 

 the southern valleys, and from the humid air of the northern 

 coast to the parched atmosphere of the interior deserts. 

 Widelv distributed over the state the ubiquitous deer mouse 



The Deer Mouse, Peromyscus 

 Photo l)ij E. R. Warren. 



is found with three distinct varieties of one species, one of 

 which occupies the cold humid coast region from San Fran- 

 cisco northward, another the interior, including both moun- 

 tains and valleys, and the southern coast, while a third lives 

 in the hot, arid deserts of the southeastern part. Possibly 

 a more ideal region for studies of environmental influence on 

 variation could not be found. Sumner has reared several' 

 generations of mice taken from the humid northern coast, and 

 the desert to the southern coast at La Jolla, and to Berkeley 

 on San Francisco Bay, but thus far without obtaining any 

 definite results. The imported mice remain true to their an- 

 cestry. 



