3/2 BACTERIOLOGY. 



stances be altogether wanting. The more im- 

 portant factors are the active proteid bodies 

 that are always present in the blood and tissue 

 juices. These fluids are, however, dependent 

 for their peculiar qualities upon the peculiar 

 qualities of the cell-territories, and the " speci- 

 fic " substances stimulate just those cell terri- 

 tories which are of special importance for the 

 individual diseases. 



Effectual protective inoculation and habitu- 

 ation to poison come about only through 

 the intervention of the body-cells, which are 

 stimulated to one of the infinitely various ac- 

 tivities made possible by their complicated 

 structure, and which are prompted by the stim- 

 ulus, to a mode of action differing only quan- 

 titatively from their normal activity, although 

 the action is seemingly of a qualitative char- 

 acter and unprovided for in the physiological 

 organization. The effect thus produced out- 

 lasts the transitory stimulus, because it is 

 bound up with the permanent and independent 

 cellular elements of the body. The retention 

 of the newly-acquired property depends upon 

 the condition of the body, and upon the kind 

 of stimulating substance and its manner of 

 introduction; the more profound the stimulus, 

 the more durably does it impress itself upon 

 the organism, and the better is it fitted for in- 



