1 1 8 TEXT-BOOK OF ZOOLOGY 



muscles or (as in the pig) beneath the skin, does not impede the 

 animal's movements. 



(/) Want of water is in itself sufficient to prevent any of our domestic 

 animals from crossing a large desert. The camel, on the other hand, 

 can exist without water for several days, even in the greatest heat, and 

 even for weeks if there is a fair supply of juicy plants at hand. To 

 provide against dearth of water, the animal, when it reaches a drinking- 

 place, takes in a great quantity at once as a reserve supply, a portion of 

 this water being stored within folds of the paunch, ivhich can be closed 

 (and thus converted into cells), and used afterwards by degrees as the 

 animal requires it. 



7. Only a rapid animal is able to cross the desert, with its dearth of 

 water and vegetable life. (Why ?) Its long, far-stretching legs enable 

 the camel to progress with great speed. It displays at the same time an 

 endurance much beyond that of any horse. A pack-camel can perform 

 about thirty miles a day, whilst a fleet-footed riding-camel can accomplish 

 about three times that distance. On account of its long legs and short 

 body, the camel moves the two legs of one side together. If it moved 

 them alternately, like the majority of mammals, it would tread on its 

 fore-feet with its hind-feet. In consequence of this peculiar gait, the 

 body swings from side to side (ship of the desert). 



8. The desert abounds in dangers. Its great height enables the 

 camel to survey extensive surfaces, and to observe an enemy from a 

 distance. By the help of its keen scent it can detect a spring some 

 miles off, even if it is hidden beneath the sand. By means of its highly- 

 developed sense of touch, it can discern the approach of the hot wind of 

 the desert (the simoom of the Sahara) much sooner than the traveller. 

 Eedoubling its steps, it endeavours to reach a place of safety, and in 

 many cases travellers have owed their lives solely to their camels. 



Related Species. 



In the barren steppes of Central and Eastern Asia the place of the 

 dromedary is filled by the Two-Humped or Bactrian Camel (C. 

 bactrianus). Its denser coat enables it to defy the awful snowstorms 

 of these districts. Saline plants being its favourite food, even the most 

 inhospitable salt steppes are made habitable by its presence. 



The Llama (Auchenia lama) is the most important domestic animal 

 of the inhabitants of the South American Cordilleras. It only attains 

 to about the size of a donkey, and is a true mountain animal ; its toes 

 are, accordingly, much more deeply cleft, the callous soles relatively 

 smaller, but the hoofs larger and more pointed, than in the true camels 

 (compare with chamois). Heavily loaded, the llamas, in long trains, 



