W. p. LARSON 185 



are toxic when introduced into the digestive tract. Carmichael,' however, has found 

 an exception to this rule in ricin, which he found was readily detoxified by sodium 

 ricinoleate. 



The bile soaps undoubtedly play an important role in detoxifying the bacterial 

 toxins of the intestinal tract. The intestinal tract is essentially a thirty-foot culture 

 tube which harbors a large variety of bacteria, many of which, growing under favor- 

 able conditions, undoubtedly secrete toxins. Had nature not provided an efficient 

 detoxifying mechanism in the form of the bile soaps, the host probably would not 

 have survived. Since toxins which have been detoxified with soaps are antigenic, it 

 seems reasonable to assume that through absorption of such detoxified toxins man 

 and the lower animals acquire a relative immunity to many of the pathogenic bacteria 

 to which they are daily exposed. 



Within certain limits the reaction between soap and toxin is quantitative.^ In a 

 study published from our laboratory it was shown that the toxicity of soap-toxin 

 n-uxtures depends more upon the concentration of the toxin than the actual amount 

 present. It was found, for example, that guinea pigs will tolerate an L+dose of 

 diphtheritic toxin in a i per cent solution of sodium ricinoleate provided the total 

 volume injected was at least 5.4 cc. Animals injected with this amount of toxin in a 

 I per cent soap solution, but in smaller volumes, died in periods of time varying in- 

 versely with the volume given. If, on the other hand, the toxin concentrations were 

 kept constant while varying the soap concentration, it was found that the animals 

 would tolerate an L+dose of toxin in 3.57 per cent solution of sodium ricinoleate in 

 a total volume of 1.4 cc. 



Tables I-III, which are taken from an article by the writer and collaborators in 

 the Colloidal Symposium Monograph, Volume 3,^ illustrate this point. 



These data show that there is a quantitative relationship in the reaction between 

 toxin and soap. The reaction is evidently not a true chemical union since in such 

 case soap which had reacted with one toxin should fail to react with others. This, 

 however, is not the case, as it has been found that, within limits, several toxins may 

 be detoxified with the same soap solutions. Furthermore, if the reaction between 

 soap and toxin were a chemical union, all toxins reacting with a given soap would 

 necessarily be considered identical chemically, and possibly antigenically as well. 

 Such a contention would not be tenable. Wells' found that whenever chemical differ- 

 ences can be shown between two antigens they invariably differ antigenically. 



Table III shows the effect of dilution upon a soap-toxin mixture which is nearly 

 neutral. Moderate dilution causes it to become non-toxic, while further dilution 

 causes it to become extremely toxic. 



Dissociation of diphtheritic toxin-soap mixture upon dilution may be observed 

 in mixtures which have stood for periods of time up to about ten days. Mixtures 

 which have stood for longer periods are not readily dissociated, but are nevertheless 

 antigenic. It is believed the data given in the tables support the theory cited else- 

 where that toxin exists as molecular aggregates. These aggregates are dispersed by a 



' Carmichael, E. B.: Proc. Soc. Exp. Biol, and Med., 24, 5. 1927. 



2 Larson, W. P., Halvorson, H. O., Evans, R, D., and Green, R. G,: Colloid Symp. Mono., 3, 

 152. 1925. 



3 Wells, H. G.: Chemical Aspects of Immunity. 1925. 



