Photo by Frank M. Chapman 



a tree: loaded WITH parasites 



"Tn our journey from the Gulf to the summit of the Sierra we passed through Temperate, 

 Tropical, and Boreal zones. . . . To reach conditions which are here distant but three 

 altitudinal miles we should have to make a journey of some 1,500 miles" (see text, page 536). 



538 



