132 Immunity 



perature of 65 C. loses the agglutinophores, and no longer 

 clumps the bacteria, though it retains the haptophores, and 

 when brought into contact with the bacteria combines with 

 them, producing no agglutination, but preventing the action 

 of any other agglutinogenic serum. 



Buxton and Vaughan* find that bacteria differ both in 

 their agglutinogenic powers and their agglutinability, both 

 of which must be taken into account in studying the subject. 



Theobald Smith f has shown that there are two kinds of 

 agglutinins, one of which acts upon the bacteria directly, the 

 other through the flagella. The occurrence of these two 

 bodies explains some of the inconipatible results of previous 

 experiments. 



The Technic of Agglutination Tests. The subject was 

 at first investigated with reference to typhoid fever, and a 

 large literature soon made its appearance. From typhoid 

 fever the method was extended to one after another of 

 the infectious diseases, in many of which the agglutina- 

 tion of the specific bacteria of the disease by the pa- 

 tient's serum was found to form a valuable adjunct in 

 diagnosis. While this clinical application was extending, 

 the method was finding added usefulness in the laboratory, 

 for it was at once evident that if the reaction was specific, 

 as it was soon proved to be, the agglutination of the bac- 

 teria by the serum not only proved the serum to come from 

 a patient or animal infected by a given bacterium, but proved 

 as well that the given bacterium was the one infecting. Thus, 

 the phenomena of agglutination came to be a recognized 

 laboratory method for the differentiation of bacteria of 

 similar species. 



The reaction is one of the most accurate known to us. It 

 is so specific that in the case of many organisms it is possible 

 to tell from what original source they may have come, and 

 always to tell to what variety they belong by quantitative 

 estimation. It is, moreover, a simple method for employ- 

 ment in large laboratories where animals may always be 

 kept on hand immunized against various cultures, so that 

 the specific serums may always be at hand. When these 

 animals are periodically bled, the serums can be sealed 

 in small tubes and kept an almost unlimited length of time 

 ready for use when opened and diluted. 



* "Jour. Med. Research," July, 1904. 

 f Ibid., 1904, vol. x, p. 89. 



