PTOMAINS 129 



glands; the pneumococcus tends to lodge in the lungs; the smallpox 

 virus selects the skin, etc. 



The bacterial toxins and viruses, as, e. g., diphtheria toxin and the 

 virus of smallpox, are regarded as ferments of protein nature, capable 

 of attacking native body protein and building up a specific foreign pro- 

 tein. This foreign bacterial protein is formed during the period of 

 incubation of disease when there is no effective resistance on the part 

 of the body-cells to its growth and multiplication. During this time 

 the infected person is not ill, so that the foreign protein in itself cannot 

 be toxic, and the body-cells are busy preparing and elaborating a new 

 and specific ferment that will digest and destroy the foreign protein. 

 When this new ferment becomes active, the first symptoms of disease 

 appear, and the active stage of the disease marks the period over which 

 the parenteral digestion of the foreign protein extends. These specific 

 ferments split up the foreign protein and liberate the toxic portion or the 

 protein poison; this poison is not a toxin and is not specific, but occurs 

 commonly in all proteins. 



The characteristic symptoms and lesions caused by the various 

 infectious processes are determined largely by the location of the foreign 

 protein. The poison elaborated is the same in all infectious diseases, 

 and it is the location of the infection, rather than the exact nature of the 

 infecting agent, which gives rise to the more or less characteristic symp- 

 toms and lesions of the several infectious diseases. 



Death may be produced by the too rapid breaking-up of the foreign 

 protein, and the- consequent liberation of a fatal dose of the protein 

 poison, or it may result from a lesion induced by the products of this 

 disruption, such as perforation of the intestine and hemorrhage in 

 typhoid fever, or it may follow from chronic intoxication and consequent 

 exhaustion. If recovery takes place, the individual enjoys an immunity 

 of variable duration, owing to the presence of specific ferments capable 

 of destroying the particular substrata if infection should occur. 



It is this power of body-cells, when permeated by a foreign protein, 

 to elaborate a specific antiferment by which the protein is destroyed, 

 that, in the opinion of Vaughan, forms the basis of a correct understand- 

 ing of infection and immunity. 



PTOMAINS 



It was at one time believed that the symptoms of many diseases 

 were due to the absorption of soluble basic nitrogenous substances pro- 

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