THE THEORY OF IMMUNITY 137 



meeting the disturbers are the substrate : the chairman 

 who orders them to be thrown out the provoked catalyst, 

 and those who act on his advice the complement. We may 

 even note that the " complement " not unseldom goes to 

 hospital in combination with the " toxin." In such cases 

 immunization is the operation of a body of stewards 

 capable of immediate and skilled combination. It is 

 worth notice, since it has frequently been suggested that 

 all living action is based on the same principles, that the 

 stewards are free amoeboid wandering bodies ; while the 

 audience of cells of the temporary organic body we call a 

 " meeting " stay where they are, 1 unless there is a violent 

 destructive reaction. In what we commonly call an 

 organism the white cells, being capable of rapid reproduc- 

 tion, and not stationary portions of basal functioning organs, 

 can be destroyed and replaced. Part of their normal 

 function is to die, as it is of soldiers in war. Adequate 

 military preparation is expectant immunity in a nation, 

 and an organized police force means the same in a society. 

 Again, it can be repeated that much light may be thrown 

 on many obscure physiological problems by observation 

 of the simple social processes taking place before our 

 eyes. On these lines we get wholly away from Ehrlich, 

 and perceive that, if enzymes, etc., are immune bodies, 

 immune bodies in their turn may be classed with the factors 

 of digestion among catalysts generally. 



What do we mean when we speak of the bactericidal 

 qualities of the blood ? Undoubtedly the blood-plasm, 

 when healthy, destroys or incapacitates invaders. But 

 what is the mechanism by which it does so, and among 

 what phenomena are we to class such mechanistic re- 

 actions ? I am unable to conceive that they can be any 

 other type than that which is characteristic of life generally. 



