TOXINS 111 



Most bacterial toxins are not absorbed from the intestine (botulinus 

 toxin excepted), and when introduced into the gastro-intestinal tract, 

 they are usually unable to produce symptoms and are quickly destroyed. 



An essential property of a toxin lies in the fact that we can immunize 

 a subject against it, and are able to demonstrate the presence of antitoxin 

 within the serum of the immunized animal. 



Chemical Properties of Soluble Toxins. As has just been stated, 

 the exact chemical nature of toxins is unknown. This is due principally 

 to the fact that pure toxins of bacteria are rarely obtainable, except in 

 conjunction with their associated products, such as lysins, pigments, acids, 

 etc., as well as to the great lability of the toxins. A summary of the 

 results of researches into the chemical nature of toxins would indicate 

 that they are tcJxalbumins, albumoses or allied to the albumoses. Certain 

 investigators have reported that very active toxins obtained by purifi- 

 cation processes did not give the protein reactions, yet toxins are digested 

 by proteolytic ferments, and, like proteins, are precipitated by nucleic 

 acid (Kossel). According to Field and Teague, 1 the toxins act like electro- 

 positive colloids, but diffuse faster than do proteins. Our present knowl- 

 edge of the chemistry of the true toxins has been expressed thus by Oppen- 

 heimer: "We must be contented to assume that they are large molecular 

 complexes, probably related to the proteins, corresponding to them in 

 certain properties, but standing even nearer to the equally mysterious 

 enzymes with whose properties they show the most extended analogies 

 both in their reactions and in their activities." 



Precipitation of the Extracellular Toxins. After the toxin has been 

 secured by filtration, crystals of ammonium sulphate are added in large 

 excess over the saturation point, and the whole kept at 37 C. for eight- 

 een hours. The toxin is precipitated and rises to the surface along with 

 the albumoses and peptones. This is skimmed off and quickly dried 

 with an electric fan and cold air. The residue is ground into a fine pow- 

 der and stored in vacuum tubes kept at a low temperature and in a dark 

 place. During this process there may be considerable deterioration 

 and especially with tetanus toxin. Banzhaf has obtained highly potent 

 and dried diphtheria toxin by slightly acidulating the toxin broth and 

 adding absolute ethyl alcohol up to 65 per cent.; after an hour or two 

 the slight precipitate is filtered off, quickly dried, and kept in ampules. 



Structure of Toxins. According to Ehrlich, the toxin molecule 

 consists of a main central atom or radical, with a large number of organic 

 side-chains grouped, as in other organic compounds, about this main 



1 Jour. Exper. Med., 1907, 9. 86. 



