The intestinal fluids extricate azote which combines with the alimentary 

 mass, and occupies the place of the carbon which the oxygen has taken 

 from it, to form carbonic acid. On reaching the lungs, and being again 

 exposed to the action of the oxygen of the atmosphere, this gas robs it 

 of a portion of its carbon, and as it disengages the azote of the venous 

 blood it brings about a new combination of that principle with the chyle. 

 Lastly, propelled with the blood to the surface of the skin, the atmos- 

 pherical oxygen disengages its carbon, and completes its azotisation. 

 The cutaneous organ is perhaps to the lymphatic system, what the pul- 

 monary organ is to the sanguineous system. 



The animalization of the animal substance is therefore effected, princi- 

 pally by the loss of its carbon, which is replaced by the excess of azote 

 in the animal fluids. These maintain themselves, in this manner, in a 

 due temperament ; for, continually parting with the carbonous principle 

 in the intestinal, pulmonary, and cutaneous combinations, they would be 

 over animalized, if an additional quantity of chyle did not seize the azote, 

 which is in excess. Still, this theory does not account for the formation 

 of the phosphoric salts, of the adipocire, and a variety of other products; 

 but without adopting it, to the full, one may presume, from the experi- 

 ments and facts on which it rests, that the oxygen of the atmospherical 

 air is one of the most powerful agents employed by Nature, in the trans- 

 formation of the aliments we live upon, into our substance. 



How are those animals nourished which live solely on mere animalized 

 flesh, that is, containing a greater quantity of azote, and a greater pro- 

 portion of ammonia than their own substance. In such a case, the assi- 

 milation of the aliments, consist in their disanimalization either, by the 

 co-operation of all the organs, or by the sole action of the digestive or- 

 gans, by the combination of the gastric juice with the other fluids. 



The constituent elements entering into the composition of our organs, 

 whether coming from the exterior, or formed by the vital power itself, 

 are thrown out of our body, by the different emunctories, and cease to 

 form a part of it, after remaining within it, for a limited time. The urine 

 carries along with it, an enormous quantity of azote, the lungs and the 

 liver rid us of the carbon and of the hydrogen; the oxygen which con- 

 tains eighty-five parts in the hundred, in the composition of water, is 

 evacuated by means of the aqueous secretions which carry off, in a state 

 of solution, the saline and other soluble principles. 



Among those salts there is one, but little soluble, and which, neverthe- 

 less, is of primary consequence among the constituent principles of the 

 animal economy. Phosphate of lime, in fact, forms the base of several 

 organs, it almost entirely, forms the osseous system, at an advanced pe- 

 riod of life; all the white organs, all our fluids contain a remarkable 

 quantity of that substance, of which the economy rids itself by a kind of 

 dry secretion. The outer covering is, in all animals, the emunctory des- 

 tined for that purpose; the annual moulting of birds, the fall of the hair 

 of quadrupeds, the renovation of the scales of fishes and reptiles, carry 

 off, every year, a considerable quantity of calcareous phosphate. Man is 

 subject to the same laws, with this difference, that the annual desquama- 

 tion of the epidermis, is not under the absolute influence of the seasons, 

 as in the brute creation. The human epidermis is renewed annually, as 

 well as the hair on the head and on the body; but this change is brought 

 about gradually, and is not completed in a season ; it does not take place 

 in the spring, as in most animals, nor in autumn with the fall of the leaf, 



