Bacteriology and Its Significance 45 



specific protein phenomenon and occasioned by any protein wliether 

 plant or animal. 



Along the line of such protein sensitization we have certain diag- 

 nostic applications. 



Koch's tuberculin which is prepared from the tubercle bacillus or 

 its products of growth, which are protein in chemical nature, reacts 

 markedly when persons or animals affected with active and masked or 

 incipient forms of the disease. The von Pirquet or cutaneous; the 

 Calmette or ophthalmo; the Moro, percutaneous or ointment; the thermal 

 and the Detre differential are tests of this type for tuberculosis. 



Mallein which is prepared in much the same way as tubeixulin is 

 used in the diagnosis of glanders. 



Similarly luetin, a filtered culture of the syphilis spirochaete, is 

 used to test for syphilis and gives a local reaction in 24 hours in an 

 individual afflicted with the disease. 



Hay fever, in many cases, at least, seems to be a sensitization from 

 certain vegetable proteins (pollens) followed by a reaction during the 

 pollen season. The practicability and clinical value of pollen extracts in 

 diagnosis, prophylactic and as a curative means is well known. 



Idiosyncrasy or charactertistic symptoms of poisoning due to foods, 

 such as eggs, fish, oysters, milk, cheese and cereals, among certain in- 

 dividuals may be explained along these same lines of hypersensitiveness 

 or anaphylaxis. 



Chemotherapy. 



Just as the application of antitoxins and anti-infectious sera, vac- 

 cines, and the various tests used in clinical diagTiosis are bacteriological 

 problems, so is the combating of microbic disease by use of chemicals. 

 We are here also concerned with the micro-organic cause of disease, its 

 prevention and cure. 



Before the days of bacteriology man had successfully combated 

 only two diseases: malaria with quinine and syphilis with mercury. 

 The laboratory has already accomplished wonders. Emetin, the active 

 principle of ipecac, has been found to be specific for amoeba. 



The injection of pure chemical substances into the body in curing 

 disease was early thought of. Most everything under the sun was tried 

 sooner or later. An example of this chemical work was the injection 

 of sodium carbonate in an effort to so change the reaction of the body 

 that the organism could not grow. 



The discovery of anti-sera sidetracked this work but it was revived 

 in a different spirit in 1900 when investigation of protozoal forms be- 

 came important as pathogenic organisms. The "ultima thule" was 

 Ehrlich's "Therapia sterilisans magana", that is, to kill everything at 

 once — complete sterilization. 



In the treatment of humans different conditions are involved and 

 one cannot always use one large sure-cure dose. It, therefore, is most 

 desirable and is the aim of this whole line of therapy to select a drug 

 which has specific and parasitotropic properties (having greater affinity 

 for the parasite than for the tissue of the host) . It was noted that 

 if a large enough dose cannot be injected so as to kill all the micro- 



