OF THEIR RESPIRATION. 575 



conditions are owing to the expansion of his 

 lungs, and the developement of the muscular 

 system by active exercise, by which he is disen- 

 cumbered of all useless fat ; so that the greater 

 part of his blood and vital energy are expended 

 on the organs of locomotion.* Besides, we are 

 informed by Darvill, that, while in training, he 

 requires fifteen quarts of oats daily, which must 

 afford about 12 Ibs. of actual nourishment. It is, 

 therefore, obvious, that a larger amount of carbon 

 and hydrogen is given off in the lungs of the 

 race-horse than in those of the ordinary horse, 



* For the same reason, the goat, sheep, deer, ox, hog, ass, and 

 many other animals, are more active in the wild state than when 

 domesticated, over-nourished, and prevented from taking much 

 exercise. The wild buffalo, or bison, is no less remarkable for 

 the size of his chest than for strength and swiftness in running, 

 compared with the tame and unwieldy ox. The wild ass, also, is 

 scarcely surpassed in fleetness by the finest horse, although slow 

 in his general movements when made a mere beast of burden. 

 But even then his muscular strength is superior to that of man ; 

 for I have observed that a small donkey, supposed to weigh about 

 170 Ibs. is capable of carrying to market, without any apparent 

 difficulty, a burden of 250 Ibs. including the rider, a distance of 

 four miles, which is certainly more than the stoutest London por- 

 ter could perform. We are, therefore, authorized to conclude, that 

 all animals whose power of obtaining caloric from the atmosphere 

 by respiration exceeds that of man, surpass him in the powers 

 of digestion, secretion, nutrition, and muscular motion. The re- 

 productive power of the rabbit, hare, cat, dog, hog, and other 

 animals of hot temperament, is also greater than in man, greater 

 in nearly all the different species of birds and mammalia, espe- 

 cially those of small size, during summer than winter, when they 

 are less playful and sprightly. 



