1 68 Changing Plant and Animal Nature 



we have in both cases portions of the same individual Uving 

 in different environments. Indeed we can leave a plant grow- 

 ing in the soil and bend a single branch into the water and see 

 it there assume an appearance characteristic of a water plant, 

 while the rest of the same individual has broad leaves char- 

 acteristic of an air dweller. 



Fig. 41. Climatic Variation in Color and Size of Song Sparrow 



The typical form is the Eastern song sparrow, Mclospiza melodia, 7. i. Aleutian, 

 M. tanaka; i. Sooty, M. rnfiua; 3, Heermann's, M. heertnanni; 4, Mountain, M. 

 motttatta; 5, Desert, M. melodia fallax; 6, Mexican, M. Mexicatia. From photograph 

 of mounted specimens, courtesy American Museum of Natural History. 



It is a matter of common observation that a group of 

 plants or animals occupying a very large area is frequently 

 made up of sub-groups that show distinct regional variations 

 (see Fig. 41) . A wild pigeon of the genus Scardafella 5hows 

 a fairly constant type of plumage in North and Central 

 America. Farther south toward the tropics there are several 



