148 FROM FISH TO PHILOSOPHER 



is roughly 1300 cc. per day, and consequently he must 

 supplement his dry food with liquid. 



Some animals, however, are so well specialized for 

 arid life that they can live on the metabohc water of 

 their food plus such preformed water as is invariably 

 present if the food is not oven-dried. One of the first 

 students to see the importance of this problem was S. M. 

 Babcock of the Agricultural Experimental Station of the 

 University of Wisconsin. Babcock was at the time con- 

 cerned with the viability and germination of seeds, but 

 secondarily he was led to demonstrate that clothes 

 moths, grain weevils, dry-wood borers, bee moths, and 

 Others, as well as their larvae, subsist wholly upon met- 

 abolic water. He showed that clothes moths will live and 

 lay viable eggs when kept in a desiccator the air of which 

 has been dried over sulfuric acid, and when feeding on 

 a piece of oven-dried woolen cloth; and that they will 

 live when fed on dry mink or astrakhan— the second gen- 

 eration dying of starvation only when every particle of 

 fur has been consumed, leaving the white, clean skin. 

 The larvae at various stages contained from 57.7 to 59.8 

 per cent water, the woolen cloth or fur only 6.1 to 9.1 per 

 cent— in other words the animal literally manufactured 

 water from its food. The larvae of the bee moth (con- 

 taining from 57.3 to 59.2 per cent water) can live on the 

 dry wax of the honeycomb, which contains less than 2, 

 per cent water, while obtaining its nitrogen from adher- 

 ing pollen grains. And so it is with the pea weevil, the 

 confused flour beetle, the flour moth, the tobacco horn- 

 worm— all Uve on food containing less than 10 per cent 

 preformed water. 



A well-dried piece of mink, astrakhan, or wool as the 

 sole source of water may well be taken to epitomize 

 'desert life,' but the reptiles and mammals have invaded 

 desert areas in a broader and more active sense. Biolo- 

 gists use the word 'desert' to designate places in which 

 the climate is hostile to animals and plants (though few 



