350 POISONS, CONTAGIONS, MIASMS. 



their own state of decomposition to substances 

 much less prone to change of composition than the 

 blood. When placed in contact with a solution of 

 sugar, they cause its putrefaction, or the trans- 

 position 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 mere produced, exactly in the same 

 manner as gluten in a state of decay or putrefac- 

 tion 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 nature 

 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 illus- 

 tration. But when the phenomena attending the 



