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force appears, also, in his explanation of the manner in which 

 poisons and medicines act. The manner in which inorganic 

 poisons (medicines) gain admission to the tissues is -owing, in 

 most cases, to the formation of a chemical compound by the 

 union of the poison with the constituents of the organ upon 

 which it acts ; it is owing to a chemical affinity more powerful 

 than the vitality of the organ. Each of these substances, in 

 its transit, produces a peculiar disturbance in the organism ; in 

 other words, they exercise a medicinal action upon it, but 

 they, themselves, suffer no decomposition. It is only when 

 the solutions are diluted to a certain degree with water that 

 they are absorbed by auimal tissues. In respect to this 

 physical property of the animal tissues, alcohol resembles the 

 inorganic salts. 



Miasms and contagions were thus explained: "A miasm is 

 a form of molecular force developed during the decomposition 

 of vegetable bodies under certain peculiar circumstances, 

 which has the power of setting up similar decompositions in 

 the human blood ; but not finding in the blood or tissues the 

 proper substance for its own reproduction, like yeast in sugar, 

 it is not reproduced. Therefore, such diseases are not con- 

 tagious." 



" Contagious poisons find in the human blood and tissues 

 substances from which they reproduce themselves, as yeast in 

 must or wort is reproduced from the gluten ; consequently, 

 these diseases are conveyable from the sick to the well ; in 

 some instances by contact only, as in syphilis, in which case 

 the physical form of the substance is that of a solid. In 

 other instances through the air, in which case the physical 

 form is that of a gas." He says, "several kinds of contagions 

 are propagated through the air ; so that, according to the view 

 already mentioned (of a contagium vivum), we must ascribe 

 life to a gas, that is, to an aeriform body." 



