364 POISONS, CONTAGIONS, MIASMS, 



result of a peculiar influence dependent on chemi- 

 cal forces, and in no way connected with the vital 

 principle. This influence is destroyed by chemical 

 actions, and manifests itself wherever it is not sub- 

 dued by some antagonist power. Its existence is 

 recognised in a connected series of changes and 

 transformations, in which it causes all substances 

 capable of undergoing similar changes to parti- 

 cipate. 



An animal substance in the act of decomposition, 

 or a substance generated from the component parts 

 of a living body by disease, communicates its own 

 condition to all parts of the system capable of enter- 

 ing into the same state, if no cause exist in these 

 parts by which the change is counteracted or 

 destroyed. 



Disease is excited by contagion. 



The transformations produced by the disease 

 assumes a series of forms. 



In order to obtain a clear conception of these 

 transformations, we may consider the changes which 

 substances, more simply composed than the living 

 body, suffer from the influence of similar causes. 

 When putrefying blood or yeast in the act of trans- 

 formation is placed in contact with a solution of 

 sugar, the elements of the latter substance are 

 transposed, so as to form alcohol and carbonic 

 acid. 



A piece of the rennet-stomach of a calf in a state 

 of decomposition occasions the elements of sugar to 



