256 Chapter IX 



that feebly agglutinative serums of persons convalescent from typhoid 

 fever may exhibit a great capacity for fixing the cytases. Other 

 facts, to be mentioned later, confirm the real difference between the 

 fixative and the agglutinative properties. 



The agglutination of bacteria was noted during the course of a 

 series of researches on the acquired properties of the blood serum of 

 vaccinated animals. Charrin and Roger 1 , seeking to obtain a clear 

 idea of the difference between the serum of normal animals and that 

 of animals vaccinated against the Bacillus pyocyaneus, observed that 

 this bacillus developed in the normal fashion in the former, but in 

 the latter gave rise to special forms of growth. Instead of growing 

 in the form of rods, it elongates into segmented filaments which 

 become entangled and fall to the bottom of the tubes, leaving a 

 supernatant limpid serum. I was able not only to confirm the 

 accuracy of this observation for the Bacillus pyocyaneus, but to 

 extend it to Gamaleia's vibrio and to the pneumococcus 2 . In all 

 these instances we have a modification of the bacteria developed 

 in specific serums coming from vaccinated animals. Later, Bordet 3 , 

 during his researches on the bacteriolysis of vibrios in vitro, observed 

 that these vibrios, when introduced into the blood serum of vacci- 

 nated animals, lose their movements and soon unite into more or 

 less voluminous masses. This observation was confirmed by Gruber 

 [270] and Durham 4 , who were the first to apply it in the specific diagnosis 

 of bacteria. They showed that the agglutinating power of vacci- 

 nated animals, although not rigorously specific, might, nevertheless, 

 be utilised for the differentiation of certain bacteria, especially the 

 cholera vibrio and the typhoid bacillus. But, independently of 

 this result, Gruber 5 essayed to formulate a theory of acquired im- 

 munity based on the agglutinative property of the serum. He 

 accepted, in connection with the phenomenon of the destruction of 

 the bacteria, Bordet's hypothesis of the concurrent action of two 

 substances, of which one, the bactericidal substance proper, is nothing 

 but the alexine of Buchner, the second being that which agglutinates 

 the bacteria. This agglutination, according to Gruber, results from 



1 Compl. Rend. Soc. de Bid., Paris, 1889, p. 667. 



2 Ann. de Flnst. Pasteur, Paris, 1891, t v, p. 473. 



8 Ann. de VInst. Pasteur, Paris, 1895, t. ix, p. 462. 



4 Miinchen. med. Wchnschr., 1896, S. 285 [cf. also Durham. Journ. Path, and 

 Bacterial., Edin. and London, 1897, VoL iv, p. 13, and 1901, VoL vn, p. 240; Brit. 

 Med. Journ., London, 1898, Vol. n, p. 588]. 



6 Wien. klin. Wchnschr., 1896, SS. 183, 204. 



