THEVOICEOFTHEDESERT -jQ^ 



with sixty-five percent for the white rat. He does save in 

 another way because, unUke most mammals, he uses no 

 water for heat regulation either by sweating from the pores 

 of the skin or from the mouth by panting. As pitiless ex- 

 perimenters have demonstrated, only when subjected to 

 heat of a nearly fatal degree will he slobber slightly at the 

 ^outh, thus using a little of the precious water to try to 

 rtave himself in extremity. And one reason for his nocturnal 

 habit probably is that he can keep relatively cool in his 

 burrow during the day, thus avoiding the risk of being 

 called upon to pant. 



But no economy can explain a complete getting along 

 without. Dipo's secret is simply — if you can call it simple 

 — that he manufactures his own water from the dry ma- 

 terials present in starchy foods. In one sense the chemistry 

 is elementary enough. Starch is a hydrocarbon and there- 

 fore contains hydrogen. Oxygen is abundant in the air he 

 breathes. And as every high school student of chemistry 

 knows, water is H2O — or a chemical combination of one 

 part oxygen with two parts hydrogen. You can make it by 

 one of the simplest of laboratory experiments if you ex- 

 plode a mixture of the two. But you- can't do it effectively 

 enough in your own body, as Dipo does, who takes it all 

 in a day's work. The result is what the biochemists call 

 "the water of metabolism" and for Dipo, with his very un- 

 usual metabolism, it is no doubt a routine matter. The only 

 way you can force him to drink is to feed him on a diet so 

 largely protein that he does not get enough hydrocarbon 

 to furnish him with hydrogen. In that unhappy state he 

 will drink water — I wonder if it tastes very nasty — when 

 it is given him. 



If in one sense this is all simple enough, in another it 



