88 ANIMAL LIFE IN DESERTS 



importance, for the hornet was a filthy feeder and 

 was frequently loaded with bacteria derived from 

 the human intestine. 



Among the large mammaHa there are many species 

 which drink, and drink freely, when an opportunity 

 is given them, but which are able to dispense with 

 drinking when it is necessary. They derive a 

 considerable quantity of water from the vegetation 

 which they eat, and one need hardly say that the 

 amount of vegetation, and of moisture in it, varies 

 very greatly with the season. Thus Doughty ob- 

 served in Arabia that " the camels now feeding in 

 the sappy rabbia (spring pasturage) were jezzin or 

 'not drinking.' In good spring years they are 

 in these diras almost two and a haK months jezzin, 

 and are not driven to the watering." Gregory 

 quotes very similar facts from Australia : he says 

 that in 1891 Tietkin marched 537 miles in thirty-four 

 days without watering his camels, and that PhilUpson 

 kept a herd without water in a sand-hill country 

 for two months. On the other hand, if very httle 

 grazing, or none at all, can be obtained and if camels 

 are doing hard work, their endurance is very much 

 less. Augieras speaks of sixteen days' march without 

 water in the Central Sahara as a severe trial to his 

 camels, and Haywood gives one to understand that 

 about eight days is near the camel's Hmit in mid- 

 summer in Tanezruft, a district of the Sahara which 

 at that season is entirely devoid of any grazing. 

 Camels not only possess this remarkable power of 

 abstaining from drinking for long periods, but they 

 are able to drink salt and bitter water which man 



