Bacteriology and Its Significance 43 



been seized upon by manufacturers with their list of shotgun vac- 

 cines and bacterines. 



Shortly after von Behring, '90, discovered that immune serum pos- 

 sessed antitoxic properties it was noted that it had other specific reac- 

 tions which bear a very practical significance from the standpoint of 

 clinical diagnosis. 



In setting forth the reasons for the reactions of immune sera, it 

 was conceived that various body fiuids possessed anti-microbic properties 

 or were anti-infectious due to cytolytic (cell dissolving) action. This 

 was nicely illustrated by Pfeiff'er's work in 1894. He showed that when 

 virulent cholera germs are injected into cholera immune animals that 

 the vibrio finally fell into granules and dissolved apparently "like sugar 

 in water". This lytic or cytolytic action is spoken of as Pfeiffer's 

 phenomenon. 



This led directly to the demonstration that as a general proposition 

 when any foreign protein is introduced into the animal body certain 

 reactions are set up. 



Among such immune bodies generated are agglutinins, precipitins 

 and lysins. The phenomenon of agglutination, which is the clumping 

 together of micro-organisms by a specific serum, was first noticed by 

 Pfeiffer but no attention was paid to it. 



Through the efforts of Widal, Gruber and Krause it was noted 

 that its practical application was twofold: (1) the recognition of dis- 

 ease and (2) the identification of the organism. In the former case 

 the serum of the suspected typhoid fever patient is brought in contact 

 with a known typhoid fever bacillus and if the phenomenon (Widal 

 test) occurs a positive diagnosis is made. While in the latter instance 

 the blood serum is known to cause agglutination with a specific organism. 



Precipitation is the combination of a soluble protein substance such 

 as blood, serum, egg white, meat extract, bacterial filtrates, etc., and 

 the corresponding immune serum, resulting in the foi-mation of a floc- 

 culent precipitate. And thus it too can be used to identify disease and 

 various soluble protein substances, such as may appear in blood stains. 

 This may be important from a legal medical standpoint or in deter- 

 mining the source of meat as in the case of sausage suspected of con- 

 taining horse or even dog flesh. 



Lysis is the disintegration of organized cells (plant or animal) by 

 specific immune serum. Bordet and Gengou first noticed this lytic action 

 of immune serum. It was observed that it was comparable to gastric 

 digestion in that there is a substance (immune body, sensitizer, ambo- 

 ceptor) which is not easily destroyed by heat (thermostable) and in 

 that respect resembles the hydrochloric acid. Another substance (alexin, 

 complement) is readily removed (thermo-labile, 56° C.) and is similar 

 to the pepsin of the gastric fluid. The latter is present in all normal 

 blood. When bacteria are thus dissolved it is referred to as bacteriolysis; 

 when red blood cells are destroyed it is known as hemolysis, etc. 



These reactions are specific. Consequently injections of red blood 

 cells of human source or typhoid fever germs, etc., into animals produce 

 the development of antibodies (lysins) which have the property of dis- 

 solving only the substance (antigen) which caused their appearance. 



