132 CHEMISTRY OF BACTERIA ASD THEIR PRODUCTS 



give a satisfactory biuret test. These toxic materials are evidently 

 quite different from either the true soluble toxins or the endotoxins, 

 since they resist heatinp: for ten minutes, at 110° in the autoclave 

 with 1 per cent, sulphuric acid, this being- a method used for securing 

 the substance. Since the sarcinas and B. prudigiosus also yield similar 

 toxic products, they cannot be considered as the specific toxic 

 substances of the pathogenic bacteria, but apparently are com- 

 mon to all proteins of whatever origin. With some bacteria the split- 

 ting process with sulphuric acid separates completely the toxic from 

 the non-toxic insoluble bacterial substance,'' e. g., B. coli communis; 

 with others a toxic portion remains insoluble. The colon bacillus pro- 

 tein gives all the protein reactions, is synthesized on Uschinsky's 

 medium, and does not yield a reducing carbohydrate. From B. 

 fifphosiis about 10 per cent, by weight of protein can be split off by 

 dilute acid, of which at least a part seems to be a phospliorized glyco- 

 protein.'^ Poisonous substances have also been obtained from B. diph- 

 therice, B. anthracis, B. tuherculosis ^ and B. pyocyaneus. They pro- 

 duce death without the usual latent period obsen'ed with toxins, and 

 are very toxic, a few (10-20) milligrams of colon bacillus poison kill- 

 ing guinea-pigs in less than ten minutes.'' A certain degree of immu- 

 nity can be obtained against them.^° Their relation to endotoxins has 

 yet to be determined. 



BACTERIAL PIGMENTS i^ 



The formation of pigment by bacteria seems to be, for the most 

 part, an adventitious, unessential property. There are a few bacteria 

 wliicli possess pigments of the nature of chlorophyll, or allied to it, 

 and this pigment is undoubtedly of great importance in the life 

 processes of these particular forms. Other varieties of pigment- 

 forming bacteria, of which but very few are pathogenic {Bacillus 

 pyocyaneus, B. proteus fluorescens, S. pyogenes aureus and citreus, 

 M. cereus flavus), seem to produce pigment as a waste product which 

 is excreted from the cell as fast as formed. Generally the pigments 

 are produced in a colorless form (leuco-hase) which is oxidized by the 

 air into the pigment, e. g., in pyocj/aneus infections the soiled dress- 

 ings are most colored about the portions most exposed to air. Since 

 pigment-forming bacteria produce pigments only under certain condi- 

 tions, and can grow abundantly without producing any pigment, it 

 is evident that the pigment formation is no very essential part of 

 llicif iiK'tjiholisiii. It is ])()ssi])](' to modify pigment ])r()ducti()ii al- 



G Wlioelcr, Jour. Amor. ^Tcd. Assoc, 1905 (44), 1271. 

 ■! Ihid., in04 (42). 1000. 



«S(>o White and Avery, Jour. IVfed. Pxes., 1912 (20), 317. 



Jour. Amcr. ]\Ied. Assoe.. lOOfi (44), 1.340; American Medic iiie. inO.l (10). 14"!. 

 lOVaufrhan (Jr.), Jour, of INIed. riesearch, 1905 (14), ()7. 



13 For complete bibliography and r^surn^ see Sullivan. Jour. ^led. Research, 

 1905 (14), 109. 



