BACTERIAL POISONS. 193 



In spite of the fact that agglutination has been found to take 

 place spontaneously in cultures, it is, nevertheless, in the main 

 a specific reaction, and is employed as an aid in the diagnosis 

 of typhoid fever, where it is spoken of as the Widal or Gruber- 

 Wiclal test. Under proper precaution it is valuable in this 

 special case, and will be referred to again in connection with 

 the description of the typhoid bacillus. 



Other bacteria which agglutinate with the homologous 

 sera are: Spirillum of cholera, B. pyocyaneus, B. proteus, B. 

 coli communis, Micrococcus melitensis, B. mallei, B. tuberculo- 

 sis, Diplococcus pneumoniae, B. pestis bubonicae, and B. 

 dysenteriae. Trypanosomes also agglutinate with homologous 

 sera. 



Lysins. There are certain substances found normally 

 present or produced artifically in the blood which have the 

 property of breaking up foreign red blood-cells introduced 

 into the circulation or into the blood-serum outside the body. 

 This is not only true of red blood-cells, but certain bacteria 

 also become broken up when introduced into the blood of 

 certain animals. This process is spoken of as cytolysis, and 

 when occurring in red blood-cells, is called hemolysis; in 

 bacteria, bacteriolysis. The substances causing cytolysis are 

 called lysins. Lysins have also been obtained from cultures 

 of bacteria. Thus Besredka* obtained a cytolysin, strcpto- 

 lysin by filtering virulent cultures of streptococcus strongly 

 hemolytic for the red corpuscles of many animals. Reudigerf 

 corroborated Besredka's work and extended his observations 

 upon the nature of streptolysin. As already stated, lysins 

 for certain foreign cells are normally present in the serum of cer- 

 tain animals; thus, human red blood-cells are disintegrated by 

 sheep's serum, rabbit's blood-serum disintegrates anthrax bacilli, 

 andnumerous other examples exist of lysin normally present in 



* Ann. de PInst. Past. 1901, No. 15, p. 880. 



f Jour. In]. Dis. Vol. IV., No. 2, April 10, 1907. pp. 277-281. 



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