92 PRINCIPLES OF BACTERIOLOGY 



Pyocyanin (C 14 H 14 N 2 O), which produces the color of blue or blue- 

 green pus, is a ptomainic pigment. Similar bodies of a basic nature 

 may be found in the intestinal contents as the products of bacterial 

 decomposition. Some of these are poisons and can be absorbed into 

 the body. Some believe the symptoms designated as coma and tetany 

 may be ascribed to the absorption of substances of this nature. Since 

 the name ptomain was given to the poisonous products of bacterial 

 growth before these products were chemically understood it is by many 

 wrongly applied to all poisons found in food, as in cases of poisoning 

 due to decomposing meat or sausage or to cheese or milk. These are 

 sometimes true toxins or even living bacteria. 



The isolation of these substances can here be only briefly referred to. 

 According to Brieger's method, which is the one now generally em- 

 ployed, the cultures having a slight acid reaction (HC1) are boiled down, 

 filtered, and the filtrate concentrated to a syrupy consistency, dissolved 

 in 96 per cent, alcohol, purified and precipitated by means of an alco- 

 holic solution of bichloride of mercurv. 



THE MORE COMPLICATED PROTEID POISONS. 



These are divided into bacterial proteins, toxins, and endotoxins. 



Bacterial Proteins. These substances are bacterial poisons which are 

 little or not at all specific, that excite fever, inflammation, and suppu- 

 ration, and resist the boiling temperature. They are usually extracted 

 by boiling cultures in 0.5 per cent, sodium hydrate solution. The pro- 

 teins are precipitated in weak acid solutions. Tuberculin is the most 

 important of the group; mallein is another. 



Like mallein, according to Buchner and Romer, all bacterial proteins 

 are very similar in their action, and Matthes maintains that deutero- 

 albumose, which is obtained by the action of pepsin on albumin and 

 has no connection with bacteria, has an effect on tuberculous guinea- 

 pigs somewhat similar to tuberculin. 



Toxins. Toxins are poisonous synthetical products of bacterial 

 growth. 



The exact composition of toxins has not as yet been discovered, but 

 it is believed that they are of proteid character. At first all the toxins 

 were supposed to be albumins, but recently some of the most important, 

 such as those produced by the tetanus and diphtheria bacilli, have been 

 shown to possess characteristics which separate them from that class. 

 Toxins are formed during the growth of bacteria in media containing 

 no proteid, but more abundantly when it is present. Toxins are divided 

 into extracellular and intracellular poisons. Thus, the toxins produced 

 by the diphtheria and tetanus bacilli during their growth in the tissues 

 or culture media are largely given up to the culture fluid, but little 

 remaining in the bacterial protoplasm, while the toxins elaborated by 

 the typhoid, tubercle, glanders, and colon bacilli, and indeed by the 

 majority of parasitic and saprophytic bacteria, are largely retained in 

 the bodies of the bacteria until their death and destruction. 



