THEIR MODE OF ACTION. 361 



preponderance. Numerous modifications in the 

 composition and condition of the compounds pro- 

 duced from the elements of the blood, result from 

 the conflict of the vital force with the chemical 

 affinity, in their incessant endeavour to overcome 

 one another. 



All the characters of the phenomena of contagion 

 tend to disprove the existence of life in the conta- 

 gious matters. They without doubt exercise an 

 influence very similar to some processes in the 

 living organism ; but the cause of this influence is 

 chemical action, which is capable of being subdued 

 by other chemical actions, by opposed agencies. 



Several of the poisons generated in the body by 

 disease lose all their power when introduced into 

 the stomach, but others are not thus destroyed. 



It is a fact very decisive of their chemical nature 

 and mode of action, that those poisons which are 

 neutral or alkaline, such as the poisonous matter of 

 the contagious fever in cattle, (typhus contagiosus 

 ruminantium,) or that of the small-pox, lose their 

 whole power of contagion in the stomach ; whilst 

 that of sausages, which has an acid reaction, retains 

 all its frightful properties under the same circum- 

 stances. 



In the former of these cases, the free acid present 

 in the stomach destroys the action of the poison, 

 the chemical properties of which are opposed to it ; 

 whilst in the latter it strengthens, or at all events 

 does not offer any impediment to poisonous action. 



