TOXINES. 5 



groups, a haptophore group, whose function it is to enter into 

 combination with the attacked cells, and a toxophore group, which 

 produces the toxic effects. Every substance that possesses a 

 specific affinity, a suitable haptophore group, for definite com- 

 plex groupings of protoplasm, is a haptine, and every poisonous 

 haptine that also possesses a toxophore group is a toxine. We 

 must therefore base our definition of a toxine in accordance 

 with this, and rigorously exclude from the toxines any poisonous 

 substance that is not a haptine and that does not produce an 

 antitoxine. 



This has been much more easily done in the case of mineral 

 and vegetable poisons, for no one would dream of including 

 among the poisons, in the narrower sense, the alkaloids, &c., 

 of plants, or the few poisonous crystalline substances that can 

 be isolated from the secretions and organs of animals, such as, 

 for example, the alkaloids in the skin of the toad, adrenaline, &c. 



But it is of much more importance to effect a classification 

 of bacterial poisons by means of this sharp definition. We 

 must, in the first place, separate from the toxines all non-specific 

 substances as defined above, from whatsoever bacteria obtained. 



But a still further classification is introduced by the fact that 

 there are probably specific bacterial poisons, which are only pro- 

 duced by definite groups of bacteria, and exert specific activity, 

 but which are not haptines, do not form anti-bodies, and are 

 therefore not toxines. Poisons of this nature appear to play a 

 part e.g., in tuberculosis. They will be shortly discussed in 

 the special part. In addition to these there is a whole series 

 of very imperfectly known bacterial poisons, whose specific 

 nature and toxine character there are strong reasons for 

 doubting. 



Most difficult of all is the question of the poisons produced 

 by certain bacteria, notably those of cholera and typhus. Their 

 toxines are scarcely known in the free state, and the poisons 

 excreted by them do not appear to be the true toxines. On the 

 other hand, we find among them another type, which presents 

 great difficulties in the way of closer investigation. These are 

 the endotoxines, which are firmly attached to the living cells, 

 and are thus comparable with the endo-enzymes of yeast and 

 animal organs. We shall discuss these more fully in a subse- 

 quent chapter. 



On Toxines in General. The true toxines, as defined above, 

 are characterised, we repeat, by their physical and chemical 

 properties in the aggregate, which we have now to describe 

 more closely, combined with their fundamental property of 



