MIRACLES OF SCIENCE 



I feel convinced that its discovery is to mark a great 

 era in medicine." 



PRINCIPLES OF THE NEW METHOD 



The method itself has features of picturesque inter- 

 est aside from the importance of its results. In prin- 

 ciple the rationale of the method is simple enough, 

 though of course a considerable degree of bacterio- 

 logical skill is necessary in practice. 



The essence of the method is this: To cultivate 

 the germs of a given disease in a culture tube; to 

 kill them by heating to about 60 degrees Centigrade ; 

 and to inject a small quantity of the culture, incorpo- 

 rating a rather definite number of dead germs, with 

 a hypodermic syringe into the tissues of the person 

 who is to be made immune to disease. 



But how, it may be asked, can good results accrue 

 to an individual through the wilful introduction into 

 his system of the germs of disease? 



The answer supplies us a clue to the entire mystery 

 of immunity. To understand it we must note a re- 

 markable property of the body tissues. It appears 

 that one extraordinary characteristic of the cells of 

 living animal tissue is this: They attempt to repel 

 any attack made upon them by producing an antidotal 

 substance specifically calculated to neutralize or op- 

 pose the attacking agent. 



If a noxious bacterium finds its way into the blood 

 and comes in contact with the tissues, the tissue cells 

 (an'd also probably the white blood corpuscles) at 

 once endeavor to produce substances that will an- 

 tagonize that particular bacterium in several char- 



210 



