604 PATHOGENIC MICROORGANISMS 



to 26 per cent of the residue can be extracted with ether and alcohol. 

 This material consists of fatty acids and waxy substances (fatty acids 

 in combination with the higher alcohols). The residue after alcohol- 

 ether extraction is composed chiefly of nitrogenous constituents. These 

 can be extracted with dilute alkaline solutions, and consist chiefly of 

 nucleoproteins. After removal of the so-called nucleoproteins that 

 is the material which comes down on treatment with dilute acetic acid 

 in the cold, there remains a small amount of coagulable protein and, 

 we have recently observed, small amounts of a substance that reacts 

 like Bence-Jones protein. 38 The final residue contains alcohol precip- 

 itable substances proteoses and polypeptids that constitute the active 

 substances of the tuberculin reactions. Cellulose is also found and is 

 supposed to represent the framework of the cell membrane, and there is 

 an ash rich in calcium and magnesium. 



Toxins of the Tubercle Bacillus. THE TUBERCULINS. Filtrates of 

 bouillon cultures of Bacillus tuberculosis 39 will occasionally produce 

 slight emaciation when injected into guinea-pigs, and when adminis- 

 tered to tuberculous subjects in sufficient quantity will give rise to 

 marked increase of temperature. It is likely, therefore, that the 

 tubercle bacillus actually secretes a soluble toxin. 40 



The chief toxic principles, however, of Bacillus tuberculosis are 

 probably endotoxins or bacterial proteins, bound during cell life to the 

 body of the bacillus. Dead bacilli will produce sterile abscesses when 

 inj ected into animals. Prudden and Hodenpyl, 41 Straus and Gamaleia, 42 

 and others, 43 moreover, have shown that the injection of dead and care- 

 fully washed cultures of this bacillus will produce lesions histologi- 

 cally similar to those occurring after infection with the living germs, 

 and will often lead to marasmus and other systemic symptoms of 

 poisoning. 



The hope of actively immunizing with substances obtained from 

 dead bacilli led Koch to employ various methods of extraction of cul- 

 tures for the manufacture of tuberculin. 



"Old Tuberculin"** (Koch) ("T.A.K."). The first tuberculin made 



88 Zinsser, Journ. exp. med., Nov., 1921. 



39 Straus and Gamaleia, Arch. med. exp., 1891. 



40 Denys, ' < Le Bouillon Filtre, ' ' Louvain, 1905. 



41 Prudden and Hodenpyl, N. Y. Med. Jour., June, 1891; Prudden, ibid., Dec. 5. 



42 Straus and Gamaleia, loc. cit. 

 43 Mafucci, Cent. f. allg. Path., 1890. 



44 Koch, Cent. f. Bakt., 1890; Deut. med. Woch., 1891. 



