MUCH CARBON. 75 



combined with it in the form of fibrine or albumen, 

 the animal receives only about 14J oz. of carbon. 

 Only about 8 oz. of this can be employed to support 

 respiration, for with the nitrogen expelled in the 

 urine there are combined, in the form of urea, 3 oz., 

 and in the form of hippuric acid, 3J oz., of carbon. 



Without going further into the calculation, it will 

 readily be admitted, that the volume of air inspired 

 and expired by a horse, the quantity of oxygen con- 

 sumed, and, as a necessary consequence, the amount 

 of carbonic acid given out by the animal, is much 

 greater than in the respiratory process in man. But 

 an adult man consumes daily about 14 oz. of carbon, 

 and the determination of Boussingault, according to 

 which a horse expires 79 oz. daily, cannot be very 

 far from the truth. 



In the nitrogenised constituents of his food, there- 

 fore, the horse receives rather less than the fifth part 

 of the carbon which his organism requires for the 

 support of the respiratory process ; and we see that 

 the wisdom of the Creator has added to his food 

 the ths which are wanting, in various forms, as, 

 starch, sugar, &c. with which the animal must be 

 supplied, or his organism will be destroyed by the 

 action of the oxygen. 



It is obvious, that in the system of the gramini- 

 vora, whose food contains so small a proportion, re- 

 latively, of the constituents of blood, the process of 

 metamorphosis in existing tissues, and consequently 

 their restoration or reproduction, must go on far less 



