G. HOWARD BAILEY S03 



valuable the phenomenon may be in vitro in identifying bacteria or in discovering 

 specific forms of infection, it is held that the process plays no essential part in the 

 protection of animals. 



EARLY OBSERVATIONS AND VIEWS ON THE FUNCTIONAL 

 SIGNIFICANCE OF AGGLUTININS 



Gengou' was unable to establish any relation between the agglutinative power 

 and the refractory state of animals to anthrax. He found that human serum may con- 

 tain large amounts of agglutinin for attenuated anthrax bacilli and yet man is far from 

 being immune to the disease. In certain cases agglutinins for a micro-organism may 

 apparently be entirely absent and yet the animal enjoy an immunity. Pigeon's serum 

 is free of agglutinins for pneumococci and yet this animal has a high degree of natural 

 immunity. It has also been pointed out that bacteria exposed to an agglutinating 

 serum are not altered in appearance, viability, or virulence. Certain clinical observa- 

 tions have tended to show that the agglutinating power of a serum gives no indication 

 of the actual degree of immunity that exists. 



Metchnikoff-" contended that agglutinins play no part, however small, in natural 

 immunity processes since he could establish no relation between the agglutinating 

 power of sera and the refractory state of man or animals to infection. Similarly, he 

 held that the part played by agglutination in acquired immunity is merely accidental 

 and subordinate. He admitted, however, that in certain special cases the immobiliza- 

 tion of very motile bacteria and their agglutination into clumps may facilitate the 

 reaction of the animal organism, especially the rapidity of phagocytosis. Besredka^ 

 had observed that guinea pigs inoculated with typhoid bacilli which had previously 

 been mixed with the blood serum of normal animals survived. Ox serum heated to 

 60° C. was the most active in this respect. The resistance of guinea pigs to bacteria 

 inoculated into the peritoneal cavity was directly proportional to the degree of pre- 

 vious agglutination of the bacilli, the organisms being readily and rapidly phagocyted 

 when in the form of clumps. These facts were interpreted by Metchnikoff as indicat- 

 ing that previous agglutination in vitro may aid in the protection of animals against 

 infection, but at the same time proved that agglutination in vivo, if it occurred at 

 all, was so feeble as to be entirely ineffective. 



Working with the cholera vibrio Salimbeni^ came to the conclusion that bacterial 

 agglutination never takes place within the animal body. In horses, goats, and guinea 

 pigs with high degrees of active or passive immunity it was found that agglutination 

 did not occur when the micro-organisms were injected subcutaneously, small amounts 

 of the exudate being removed at frequent intervals and examined. Nor was it possible 

 to demonstrate the phenomenon when the spirilla were given by intraperitoneal in- 

 jection into guinea pigs, even though the peritoneal fluid, lymph, or blood serum 

 caused almost instantaneous agglutination when mixed with the vibrios in hanging- 

 drop preparations or in the test tube. The only changes noted in vivo were loss of 



' Gengou, O.: Ann. I'lnst. Pasteur, 13, 642. 1899. 



- Metchnikoff, E.: Immunity in Infective Diseases, pp. 258, 263. Cambridge, 1905. 



■5 Besredka, A.: Ann. de I'Inst. Pasteur, 15, 209. 1901. 



4 Salimbeni, A. T.: ibid., ii, 277. 1897. 



