214 ANIMAL COMPETITOES 



experiments quiet and their results a secret; 

 but a recent investigation pursued by W. H. 

 Osgood of the Biological Survey has gathered 

 many facts as to method, of which I shall avail 

 myself liberally. 



Variability of the red fox. The common 

 fox, as has been said, varies from red to black, 

 and these extremes, with the gradations be- 

 tween them, form four more or less distinct 

 phases, respectively known as red, cross (or 

 patch), silver, and black. 



In the red phase the animal is entirely rich 

 fulvous, except restricted black markings on 

 the feet and ears, a white area at the end of the 

 tail, and certain white-tipped hairs on the back 

 and rump. From this phase to the next the 

 black increases in extent until, in the typical 

 "cross" fox, the black predominates on the 

 feet, legs and underparts, while fulvous over- 

 lying black covers most of the head, shoulders 

 and back. A gradual increase of the black and 

 elimination of the fulvous, or its replacement 

 by white, brings us to the next phase, the "sil- 

 ver, " or " silver-gray, ' ' in which no fulvous ap- 

 pears, the entire pelage being dark at the base 



