RELATIONS OF THE VEGETABLE TO THE ANIMAL KINGDOM. 207 



remainder in decay after death. The atmosphere, therefore, out 

 of which plants create nourishment, and to which animals as they 

 consume return it, forms the necessary link between the animal 

 and vegetable kingdoms, and completes the great cycle of organic 

 existence. Organized matter passes through various stages in veg- 

 etables, through others in the herbivorous animals, and undergoes 

 its final transformations in the carnivorous animals. Portions are 

 consumed at every stage, and restored to the mineral kingdom, to 

 which the whole, having accomplished its revolution, finally returns. 

 364. Plants not only furnish all the materials of the animal fab- 

 ric, but furnish each principal constituent ready-formed, so that the 

 animal has only to appropriate it. The food of animals is of two 

 kinds ; 1. that which serves to support respiration and maintain the 

 animal heat ; 2. that which is capable of forming a portion of the 

 animal fabric, of its flesh and bones. The ternary vegetable prod- 

 ucts furnish the first, in the form of sugar, vegetable jelly, starch, 

 oil, &c., and even cellulose; substances which, containing no ni- 

 trogen, cannot form a part of the animal frame, but, conveyed into 

 the blood, are decomposed in respiration, the carbon and the ex- 

 cess of hydrogen combining with the oxygen of the air, to which 

 they are restored in the form of carbonic acid and water. Any 

 portion not required by the immediate demands of respiration is 

 stored in the tissues in the form of fat, (which the animal may 

 either accumulate directly from the oily and waxy matters in its 

 vegetable food, or produce by an alteration of the starch and su- 

 gar,) as a provision for future use ; any deficiency subjects the tis- 

 sues themselves, or the proper supporting food, to immediate de- 

 composition in respiration. The quaternary or azotized products 

 furnish the proper materials of the animal frame, the fibrine, ca- 

 seine, albumen, &c., being directly appropriated from the vegeta- 

 ble food to the blood, muscles, &c. ; while a slight transformation 

 of them gives origin to gelatine, of which the sinews, cartilages, 

 and the organic part of the bones consist. The earthy portion of 

 the bones, the iron in the blood, and all the saline ingredients of 

 the animal body (with the exception of common salt, which is 

 sometimes taken directly from the mineral kingdom), are drawn 

 from the earthy constituents (336) of the plants upon which the 

 animal feeds. The animal merely appropriates and accumulates 

 these already organizable materials, changing them, it may be, little 

 by little, as he destroys them, but rendering them all back (those 



