356 BIOLOGY OF PNEUMOCOCCUS 



mation. Meager as was Metchnikoff's 894 description of the phe- 

 nomenon, it was undoubtedly he who, in 1891, first observed the 

 clumping of pneumococci in immune serum. Issaeff, 673 two years 

 later, confirmed Metchnikoff's observation, and added that the se- 

 rum of rabbits vaccinated with Pneumococcus when mixed with the 

 organism, instead of becoming cloudy, developed a deposit. It is 

 probable that in one of Mosny's 933 experiments (1892) agglutina- 

 tion took place although he interpreted the result in a different way. 

 The incubation of a culture of Pneumococcus in normal rabbit se- 

 rum was attended by a diffuse clouding of the medium with a 

 granular sediment appearing after twenty-four hours, while in im- 

 mune serum the faint cloud disappeared after eight hours due very 

 likely to the sedimentation of agglutinated cells. In 1896, Wash- 

 bourn 1486 undoubtedly observed agglutination, for he described the 

 sediment accumulating in immune rabbit serum twenty-four hours 

 after the addition of pneumococci as consisting "of pneumococci 

 staining well and grouped in masses." 



It was Bezancon and Griffon 108 " 10 who, in 1897, recognized the 

 phenomenon as agglutination and compared the effect in the case 

 of Pneumococcus to the Widal test for the diagnosis of typhoid 

 infection. Although there was no difficulty in demonstrating the 

 agglutinative properties of fluids collected from animals dying 

 from pneumococcal infections, the results obtained with serum 

 from patients suffering from similar infections were somewhat con- 

 fusing. However, Bezancon and Griffon gave a correct interpreta- 

 tion to their results in concluding that from the standpoint of 

 agglutination there existed several races of pneumococci. In the 

 first five cases of pneumonia studied, the organisms isolated ag- 

 glutinated well in immune serum and these strains were referred to 

 by the authors as vulgaire pneumococci. By the agglutination 

 method, the French workers differentiated a strain with all the 

 characteristics of Type III Pneumococcus and were therefore the 

 first bacteriologists to recognize the applicability of the agglu- 

 tination reaction to the differentiation of Pneumococcus from re- 



