TOXINS AND ANTITOXINS 51 



loids," but as yet there is little definite proof that reversible reac- 

 tions between two colloids take place. According to certain inter- 

 pretations, the most important observation in support of the 

 colloidal theory is the Danysz effect. If the toxin is added to the 

 antitoxin in fractions with an interval of time elapsing between, less 

 toxin is needed to saturate the antitoxin than if the toxin were added 

 in one volume. In other words, if i.o c.c. toxin were saturated 

 in the usual way with o.i c.c. antitoxin and if in another test-tube 

 the toxin is added to the same amount of antitoxin, not in a single 

 dose, but in successive doses of 0.2 c.c., until i.o c.c. is present, this 

 latter mixture instead of being neutral would be toxic. Wells, how- 

 ever, states that this " indicates that the toxin antitoxin union is 

 physical rather than chemical, for it seems to be quite analogous to 

 such a phenomenon as the taking up of more dye by several pieces 

 of blotting paper added in series to a dye solution, than by the same 

 amount of paper added in one piece." Of somewhat similar import 

 is the absorption theory of Bordet and of Landsteiner, which states 

 that when toxin is added to antitoxin in smaller quantities than 

 saturation, let us say five molecules of antitoxin to ten of toxin, this 

 does not result in complete molecular combination with five mole- 

 cules of toxin, but rather in half saturation of the entire ten mole- 

 cules of toxin. This results in attenuation of the toxin, so that 

 instead of there being five free molecules of toxin there are ten units of 

 partly detoxified toxin. It is not to be expected that this follows in exact 

 arithmetical progression, but Biltz has made comparisons with absorp- 

 tion phenomena in general and finds fairly consistent results. 



In summary it may be said that in explaining the union of toxin and 

 antitoxin the Ehrlich hypothesis does not withstand critical examination 

 and that the reaction is in all likelihood of an intricate physico-chemical 

 nature referable, in part at least, to the probable colloidal nature of the 

 reacting bodies, but not as yet satisfactorily explained. 



Therapeutic Use of Diphtheria Antitoxin. In 1892 von Behring 

 and Wernicke found that the serum of animals immunized against 

 diphtheria toxin protects other animals of the same and different 

 species against the action of the toxin. In 1894 Roux demonstrated 

 the value of the treatment of diphtheria in man by means of anti- 

 toxic serum. This method of treatment rapidly attained widespread 

 use and has markedly reduced the mortality from the disease. 

 Numerous statistical studies have been made since that time, and 

 it is safe to say that the introduction of antitoxin treatment has 

 reduced mortality from approximately 40 per cent, to approximately 

 7 per cent. In interpreting the figures it has been found necessary 

 to take account of two important factors; namely, the cases of 

 laryngeal diphtheria and the time at which treatment is instituted. 

 Laryngeal diphtheria presents not only the element of toxic absorp- 

 tion, but in addition mechanical obstruction to respiration and 

 the possibility of extension downward, so as to produce pneumonia. 

 Furthermore, the operative procedures for relieving the respiratory 



