MORBID POISONS. 389 



they cause its putrefaction, or the transposition of 

 its elements into carbonic acid and alcohol. 



When putrefying muscle or pus is placed upon a 

 fresh wound, it occasions disease and death. It is 

 obvious that these substances communicate their 

 own state of putrefaction to the sound blood from 

 which they were produced^ exactly in the same man- 

 ner as gluten in a state of decay or putrefaction 

 causes a similar transformation in a solution of 

 sugar. 



Poisons of this kind are even generated by the 

 body itself in particular diseases. In small-pox, 

 plague, and syphilis, substances of a peculiar na- 

 ture are formed from the constituents of the blood. 

 These matters are capable of inducing in the blood 

 of a healthy individual a decomposition similar to 

 that of which they themselves are the subjects ; in 

 other words, they produce the same disease. The 

 morbid virus appears to reproduce itself just as seeds 

 appear to reproduce seeds. 



The mode of action of a morbid virus exhibits 

 such a strong similarity to the action of yeast upon 

 liquids containing sugar and gluten, that the two 

 processes have been long since compared to one 

 another, although merely for the purpose of illustra- 

 tion. But when the phenomena attending the action 

 of each respectively are considered more closely, it 

 will in reality be seen that their influence depends 

 upon the same cause. 



In dry air, and in the absence of moisture, all 

 these poisons remain for a long time unchanged ; but 

 when exposed to the air in the moist condition, they 

 lose very rapidly their peculiar properties. In the 

 former case, those conditions are afforded which 

 arrest their decomposition without destroying it ; 

 in the latter, all the circumstances necessary for the 

 completion of their decomposition are presented. 



The temperature at which water boils, and contact 

 with alcohol, render such poisons inert. Acids, salts 

 of mercury, sulphurous acid, chlorine, iodine, bro- 



33* 



