xix.] PATHOGENIC ORGANISMS. 247 



per se can also not have this power, since we see that the 

 power to overcome the influence of the living tissue is 

 precisely the great distinguishing character of pathogenic 

 organisms. There remains, therefore, only one thing, that 

 is that there is something or other present in a particular 

 tissue to which this latter owes its immunity, and this some- 

 thing must of necessity be connected with the tissue while 

 alive, as we said before. Now, the life of the tissue in the 

 pig cannot be different from that of the mouse, if by life is 

 understood the function of the tissue, the connexion with 

 the vascular and nervous system, and all the rest of it. The 

 subcutaneous connective tissue has no different function, no 

 different relation to the vascular and nervous system in the 

 pig from what it has in the mouse, and nevertheless we find 

 that it behaves so differently in the two cases towards the 

 bacillus anthracis. This something then, which inhibits the 

 growth and multiplication of the bacillus anthracis in the 

 tissue of the pig but not in the mouse, must be something 

 which, although dependent on the life of the tissue, is not 

 identical with any of the characters constituting the life of the 

 tissue, but must be some product of that life. To assume 

 then, as is done by some observers, that the living state of 

 the cells per se is the inhibitory power does not cover the 

 facts, as we have just shown. The most feasible theory 

 seems to me to be this, that this inhibitory power is due to 

 the presence of a chemical substance produced by the living 

 tissues. It does not require any great effort to conceive, 

 and it does not seem at all improbable, that the blood and 

 tissues of the pig contain certain chemical substances which 

 are not present in the mouse, substances which like so many 

 others chemistry is not yet capable of demonstrating. But 

 that there exist vast and gross differences in the chemical 

 constitution of the blood and tissues of different species 



