82 ANIMAL LIFE IN DESERTS 



was a puzzle to the writer till it was noticed that 

 they drank drops of dew from the angles of dried- 

 up thorny plants." 



Though lack of precise observation prevents us 

 from forming a clear idea of the importance of dew 

 to the fauna, it is probably considerable, at any 

 rate at certain seasons. A more constant source 

 of supply is the desert vegetation. Plants, however 

 dead they are, and however long they have been 

 exposed to the desert wind and sun, are not chemi- 

 cally dry, any more than hay or chaff are dry. 

 It has also been suggested that during digestion 

 by an animal a certain additional amount of water 

 may be elaborated as a by-product of the break- 

 down of the complex chemical bodies of which the 

 plant consists. 



One can therefore understand that it is possible 

 for a seed-eating mammal or bird to exist for long 

 periods without eating succulent plants or drinking 

 the dew or obtaining water from any visible source, 

 and some of them can do this. I remember an 

 Egyptian Jerboa which was kept by a member of 

 my family as a pet. It was given no water and 

 lived for many months on crushed oats and bran ; 

 when it was offered apple or carrot or other moist 

 food it generally refused to eat it. That it could 

 not drink dew is certain because it Hved in a London 

 house. It is almost certain that many birds, in- 

 sects, and small mammals depend solely upon the 

 minute quantities of water to be found in seeds 

 and dead plants which have become completely 

 " air-dry." 



