TOXINS 123 



toxin for nervous tissues.""' In comnion witli other colloids they are 

 adsorbed by surfaces, such as charcoal, kaolin, etc.; such ad.sorption 

 is accompanied by little change in any of the physical properties of the 

 solution, except an increase in surface tension (Zunz). 



Differences from Ptomains. — While ptomains are formed by cleavage processes 

 from the medium upon which the bacteria grow, and the same ptomains can be 

 produced by several different kinds of bacteria, the toxins are synthetic 'products 

 of absolutely specific iiaturc. However, the toxins seem to be produced little if at 

 all by growing the bacteria on Uschinsky's or similar media, which contain no 

 proteins, carbohydrates, or fats, but merely simple organic and inorganic salts 

 of known composition.^' Nevertheless diphtheria toxin is essentially the same 

 no matter on what sort of medium the l)acteria are grown, whereas ptomains vary 

 with the nature of the siilistance from wliich they are produced. Toxins arc true 

 Sgc retions of bacterial cells, just as trypsi n is of pancre at'c c.pIIs, or tli,Y.roiodin of 

 thyroid cells. SvEi-bodies caiTTKf produced agamstt oxins, but not again st 

 ptomains. — ' ^ " ~ 



Ehrlich's Conception of the Nature of Toxins. — Chemical 

 studies of toxins being impossible, we have been obliged to study them 

 through their physiological effects, just as we have obtained informa- 

 tion concerning enzymes through their specific actions. In this way 

 Ehrlich developed well-crj'stallized ideas concerning the structure 

 of toxins, as well as the manner in which they act, which may be briefly 

 summarized as follows: Each toxin molecule consists of a large num- 

 ber of organic complexes, grouped, as in other organic compounds, 

 as side-chains about a central chain or radical. One or more of these 

 complexes has a chemical affinity for certain chemical constituents of 

 the tissues of susceptible animals, with which the toxin molecule 

 unites; this binding group is called the haptophore (meaning "bear- 

 ing a bond"). Another side-chain or group of side-chains exerts the 

 injurious effects upon the tissue to which the molecule has been bound 

 by the haptophore, and cannot produce these injurious effects unless 

 it has been so bound. This injury-working group is called the toxo- 

 pJiore. An animal is susceptible to a toxin only when its cells con- 

 tain substances which possess a chemical aflB.nity for the haptophore 

 groups of the toxin, and also substances which can be harmfully influ- 

 enced b}^ the toxophore groups. Tetanus toxin, for example, owes its 

 effects to the fact that nervous tissues contain chemical substances 

 having a strong affinit}' for the haptophore group of tetanus toxin, 

 and also substances that can be attacked with serious results by the 

 toxophore group of the toxin. The nature of the changes brought 

 about by the toxophore groups of toxins is not understood; there are 

 many resemblances to the action of enzymes, but the analogy is by 

 no means complete. We find perhaps the closest analogy to the en- 

 zymes in the toxic substances that destroy- red corpuscles and bacteria 

 (hemolysins, bacteriolysins) , which will be considered in another place. 

 The immunity against toxins and enzymes seems to be produced by 



^«Loewe, Biochem. Zeit., 1911 (33), 225, and (34), 495. 

 "See Rettgerand Robinson, Jour. Med. Res., 1917 (38), 357. 



