38 TOXINES AND ANTITOXINES. 



virus. For by their aid EHRLICH has succeeded in determining 

 the composition of toxine bouillon as regards the toxines and 

 toxoids. He has discovered the existence of extremely complex 

 relationships, and the final solution of the problems involved 

 will doubtless still furnish work for the next generation. 



The value of these limitation values in the determination of 

 the amount of toxine and toxoids in solutions of poisons depends 

 upon the following facts : 



The antitoxine unit is a measure based upon a definite toxine 

 solution. The original cannot as yet be reproduced, and its 

 value has only been preserved by EHRLICH having kept an 

 originally standardised serum of 1,700 times the normal strength 

 under special precautions (vacuum, darkness, ice, dryness), and 

 using this serum after suitable dilution to standardise new 

 toxine solutions, which then in turn can be used to test fresh 

 sera. In the original normal toxine an antitoxine unit corre- 

 sponded to 100 lethal doses ; hence, to neutralise an immunity 

 unit 100 lethal doses of this normal toxine of BEHRING would be 

 necessary i.e., L is exactly 100. But this numerical relationship 

 is not invariably necessary with all toxines, for there can also 

 be some in the case of which a large proportion of the immunity 

 unit would be fixed by non-poisonous haptines, toxoids, whose 

 quantity is expressed in toxic units i.e., L then becomes less than 

 100. This is not the case, however, with most fresh toxines, 

 for with them L is really 100, or, in other words, these fresh 

 toxines have a constitution exactly like that of Behring's normal 

 toxine. 



But the case is different when we deal with older solutions of 

 toxines, as we have already pointed out above. Here part of the 

 toxine has been converted into toxoids i.e., L has become 

 smaller, and a smaller number of toxic units in an equal volume 

 are required to reach the stage of neutrality. On the other hand, 

 there are also toxines whose relative proportion in true toxine is 

 greater than in the case of Behring's normal toxine, so that we 

 are driven to the conclusion, which is difficult to follow, that 

 even fresh toxines may contain not only poisonous haptines, true 

 toxines, but also relatively non-poisonous substances, which 

 EHRLICH has designated toxones, to distinguish them from the 

 toxoids, which are only produced as secondary products. We 

 thus arrive at the following definition of L : 



Every solution of toxine, even in the fresh condition, contains, 

 in addition to the true toxine, non-poisonous haptines, toxones, 

 which usually stand in such relationship to the true toxines that, 

 in the case of most fresh toxine preparations, L is equal to 100. 



