AGGLUTINATED TYPHOID BACILLI. 157 



usually still excited an extraordinarily strong immunity reaction, a phenomenon 

 seemingly in contradiction to Ehrlich's theory. Further experiments, however, 

 showed that when very high doses of an active cholera goat serum were em- 

 ployed, the immunizing action was almost entirely lost. Of especial importance 

 for future methodical investigations of this kind is the fact determined by these 

 authors, that a real saturation of the receptors of the cholera vibrios requires 

 a surprisingly high multiple of the amount of immune serum sufficient to dis- 

 solve the same amount of cholera vibrios. 7500 times this amount does not 

 yet satisfy all the affinities and it requires enormous doses, up to 3-4 million 

 times, to completely saturate all the receptors. 



