396 POISONS, CONTAGIONS, MIASMS. 



Food will act as a poison, that is, it will produce 

 disease, when it is able to exercise a chemical action 

 by virtue of its quantity ; or, when either its con- 

 dition or its presence retards, prevents, or arrests 

 the motion of any organ. 



A compound acts as a poison when all the parts 

 of an organ with which it is brought into contact 

 enter into chemical combination w^ith it, while it may 

 operate as a medicine, when it produces only a par- 

 tial change. 



No other component part of the organism can be 

 compared to the blood, in respect of the feeble re- 

 sistance which it offers to exterior influences. The 

 blood is not an organ which is formed, but an organ 

 in the act of formation ; indeed, it is the sum of all 

 the organs which are being formed. The chemical 

 force and the vital principle hold each other in such 

 perfect equilibrium, that every disturbance, however 

 trifling, or from whatever cause it may proceed, effects 

 a change in the blood. This liquid possesses so 

 little of permanence, that it cannot be removed from 

 the body without immediately suffering a change, 

 and cannot come in contact with any organ in the 

 body, without yielding to its attraction. 



The slightest action of a chemical agent upon the 

 blood exercises an injurious influence; even the mo- 

 mentary contact with the air in the lungs, although 

 effected through the medium of cells and membranes, 

 alters the color and other qualities of the blood. 

 Every chemical action propagates itself through the 

 mass of the blood ; for example, the active chemical 

 condition of the constituents of a body undergoing 

 decomposition, fermentation, putrefaction, or decay, 

 disturbs the equilibrium between the chemical force 

 and the vital principle in the circulating fluid. 

 Numerous modifications in the composition and con- 

 dition of the compounds produced from the elements 

 of the blood, result from the conflict of the vital 

 force with the chemical affinity, in their incessant 

 endeavor to overcome one another. 



