ANTITOXINS 25 



going much deeper into the subject the point may be 

 illustrated by the appended diagrams or " spectra." 



Fig. 2 shows the simplest conceivable diphtheria 

 poison. In this case the following values would 

 be obtained. 



x cc poison (100 fatal doses) + f antitoxin 

 units = o, i.e. absolutely neutral. 



x cc poison + M -- = Free toxon. 



x cc poison + iU --= Free toxon. 



That is to say, if the proportion of antitoxin added 

 was {} of the amount required for complete 

 neutralization, it would be found that the poison 

 thus uncombined was much less, and differently 

 toxic than a corresponding amount of the original 

 toxin. It was found that these fractions possessed 

 a rather constant though low degree of toxicity 

 with characteristic action. This consisted in the 

 production of some local oedema, followed by a 

 long incubation period, and finally the develop- 

 ment of cachexia and paralysis. Ehrlich believes 

 that this action is due to a separate poison excreted 

 by the diphtheria bacillus which he calls a toxon. 



If we continue with the above poison we shall 

 obtain these values: 



x cc poison + sV<r = Toxin action (i fatal dose). 



x cc poison + /A =30 fatal doses. 



x poison + WV = 90 fatal doses, etc. 



That is to say, if we add only & 9 ff units antitoxin, 

 i.e. sJfli unit less than in the J&J mixture, we find 



