RESISTANCE OF THE BODY 93 



tosis as the protective work of these "eating" and 

 "wandering cells" is called has said that "immunity 

 may be inborn or acquired." * * * The former is. 

 independent of the direct intervention of human art ; 

 the acquired immunity may come as the result of the 

 spontaneous cure of an infectious disease or as the 

 result of direct interference of human art, as in vac- 

 cination and similar methods now employed by phys- 

 icians to ward off an expected disease or to decrease 

 the virulence of one already contracted." 



This inborn immunity Newman calls "natural im- Natural 

 munity" and attributes it to the presence in the blood 

 of soluble matters called alexines. If the alexines are 

 present in sufficient quantity, the person is less or not 

 at all susceptible to certain diseases, although they may 

 not protect him from the attack of all disease germs. 

 These alexines protect the body perfectly from all 

 but the pathogenic bacteria. 



Phagocytosis seems to be a plausible theory so far Toxine 

 as the germs themselves are concerned, but does not 

 prove equally tenable in the case of the toxines which 

 the germs have produced. Other investigators, 

 notably Behring and Kitasato, do not believe that the 

 phagocytes are the prime protective agency in this 

 immunity. They discovered in their experiments upon 

 animals that the clear, yellowish liquid part of the 

 blood, or the bloom serum, taken from an animal that 

 had diphtheria could and did in their test tubes destroy 

 the action of the toxines of that disease. 



