458 PROTEIN POISONS 



it seems to be a biological law that when a living cell is 

 brought in contact with or permeated by a foreign protein, 

 it tends to furnish a ferment which will digest and destroy 

 the foreign body. The ferments of the cells of man's body 

 may be modified or new ones developed by (a) disease, 

 (6) vaccination, and (c) sensitization. Many of the infec- 

 tious diseases give immunity to subsequent exposure. In 

 some of the chronic infectious diseases the altered behavior 

 of the body cells to the infecting agent is evident even 

 while the disease continues. 



That the tuberculous animal behaves differently from 

 the non-tuberculous on receiving injections of the tuber- 

 culin protein, whether it be in the form of the living bacillus, 

 in dead cells, or in solution, has been abundantly demon- 

 strated. Before Koch gave us tuberculin, Arloing and 

 Courmont had come to the conclusion that the tubercle 

 bacillus produces soluble substances which reduce the 

 natural resistance of the body and render it more susceptible 

 to reinfection. This corresponds closely w T ith the first 

 impression made by observation of the phenomena of ana- 

 phylaxis; the impression that led Richet to select this 

 term. In 1891, Koch described a perfect example of protein 

 sensitization as we understand it today. He stated that 

 when a healthy guinea-pig is inoculated with the living 

 tubercle bacillus there is no change at the site of inoculation 

 until from ten to fourteen days later, when a hard lump 

 forms, finally opens and ulcerates, and continues until the 

 animal dies. On the other hand, when a tuberculous guinea- 

 pig is inoculated with the living bacillus, on the second or 

 third day a lump forms, soon becomes necrotic, falls out, 

 ulcerates for a time, and finally heals without any infection 

 of the neighboring lymph glands. In 1897 Trudeau observed 

 that when healthy rabbits receive injections of virulent 

 cultures in the eye, there is little to be seen for about four- 

 teen days, when with increasing vascularity tubercles form 

 in the iris, after which inflammation extends and the eye 

 is practically destroyed within from six to eight weeks. 

 Like treatment of tuberculous rabbits develops an iritis 



