RELATION OF TOXINES TO ANTITOXINES. 41 



difference D above the amount "one" theoretically required by 

 pure toxines. 



The relative amount of such toxones varies very considerably, 

 and hence D is also a very variable value. EHELICH found it to 

 vary from 1*7 to 28 toxic units in the case of 11 toxine solutions. 



The value D, after reduction of the finally active one toxic unit 

 (D - 1), thus affords a measure of the quantity of toxones present 

 in toxine solutions. The fact that these variations in the value 

 of D occur even in fresh toxines, and do not alter as the poison 

 becomes old, when L decreases, shows that toxones are not 

 secondary decomposition products of the toxine, but are primary 

 bacterial products non-poisonous haptines. 



As regards other physiological characteristics, toxones are not absolutely 

 inactive. Their action can be studied in what EHRLICH has termed the 

 "differential zones" i.e., between L and L+, where, according to his 

 view, free toxones are present. They produce slight toxic symptoms 

 (which we shall discuss later on), which are essentially different from the 

 effects of small non-lethal doses of toxines. 



A special importance attaches itself to the discoveries of MADSEN, that it 

 is possible to produce antitoxic immunity with the mixed poisons in the 

 differential zones, which thus only contain toxones in the free state. We 

 shall discuss this more fully in its proper place (see Diphtheria Virus in the 

 special part). 



EHRLICH next endeavoured, by means of elaborate, tedious, 

 and difficult processes, to obtain a clearer view of the quantita 

 tive relationships of the poisons and the numerical conditions of 

 their decomposition. These relationships proved to be of an 

 extremely complex character, and we do not wish to do more 

 than briefly touch upon them here. 



In the first place, EHRLICH fixed the following formula for 

 any given poison : 



x Toxoid + y Toxine + z Toxone. 



The value of y must be found by a physiological method (deter- 

 mination of the lethal dose), and is then represented by a. z, the 

 toxine value, is a function (F) of the value D - 1, which can 

 also be numerically expressed. It is designated j3 by EHRLICH. 

 Thus, the formula of every known solution of the poisons can be 

 expressed as follows : 



x Toxoid + a Toxine + F(j3) Toxone. 



The formation of toxoids is illustrated by the following experi- 

 ment : 



