4 ANIMAL LIFE IN DESERTS 



States of the Union, and in Mexico. The impor- 

 tance of these deserts to the botanist, and in a 

 secondary manner to the zoologist, lies in the fact 

 that they have been more thoroughly studied than 

 any other desert region in the world. The labora- 

 tory at Tucson, Arizona, supported by the Carnegie 

 Institution of Washington, and directed by Dr. 

 D. T. Macdougal, has contributed immensely to 

 our knowledge of the climatic and physical features 

 of the surrounding deserts, and of the influence 

 of these features upon the vegetation. 



Other desert areas are found in South- West 

 Africa and along the coast of South America, 

 from latitude 5° to 30° S., in Eastern Patagonia 

 and Western Argentina. Quite small areas of 

 desert occur in many parts of the world, and any 

 area of sand dune very closely resembles desert 

 in the scarcity of available moisture, and in the 

 specialization of its flora. 



It is not to be understood that any area described 

 above as desert is uniformly so, either in its physical 

 condition or in its flora and fauna. In the belt 

 occupied by the Great Palaearctic Desert there are 

 certain very fertile spots, for example, the delta 

 of the Nile, the highlands of Yemen, and the date 

 groves of Basra, and a similar diversity is found 

 in other desert regions. 



We shall now review the chmatic influences 

 which contribute largely to make life in a desert 

 impossible to any plant or animal which is not 

 specially adapted to it. In the mind of every one 

 the desert stands first for dryness, secondly for 



