CHAPTER IX 



Tuberculin and Mallein — Animal Toxins — Venoms 



Tuberculin and mallein — Koch's phenoraen — Action of tuberculin — Local 

 and general reactions — Resistance of tuberculin towards physical 

 agents which destroy other toxins — Specificity — No antituberculin — 

 Habituation to tuberculin — Cutaneous reaction of v. Pirquet — Tuber- 

 culin and anaphylaxis. 



Animal toxins — venoins— The venoms in the animal kingdom— Snake 

 poisons — Physiological action of venoms — Digestive properties — 

 Haemolysis by venoms — Role of lecithin — Lecithids — Natural immunity 

 of certain animals towards venoms. 



Tuberculin and Mallein 



These poisons are found in old broth cultures of the 

 bacillus of tubercle and the bacillus of glanders. They are 

 prepared by combined maceration and heat from glycerine 

 extracts of the cultures. They exist also in the bodies of the 

 bacteria and are thus in a sense endotoxins. But hitherto no 

 antitoxins to them are known. 



Tuberculin and mallein from their physiological properties 

 occupy a place apart. Tuberculin may be taken as the 

 type. 



Koch's Phenomenon. — The discovery of tuberculin 

 originated in the " Koch's phenomenon " : when tubercle 

 bacilli are inoculated subcutaneously in a guinea-pig nothing 

 is seen at the point of inoculation for from ten to fourteen days, 

 then a nodule appears which later produces an open sore, 

 which refuses to heal ; the corresponding lymphatic glands 

 are swollen. If, however, a guinea-pig already tuberculous is 

 reinoculated after four to six weeks, there appears on the third 



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