QUALITATIVE BACTERIOLOGICAL ANALYSIS. 95 



experiments on the action of coli-serum on different races of 

 B. coli showed that the serum always acted in the highest 

 dilution on the variety used to inoculate the animal. Very often 

 the serum had no action on other varieties ; but when it did 

 act the dilution was much lower than that which agglutinated 

 the bacillus used for the preparation of the serum. He also 

 showed that ,in the stools of the same person several varieties 

 of B. coli might appear. 



Lee Smith showed that all the B. coli cultures isolated from 

 the stools of a child " at the breast " were agglutinated by a 

 serum made with any one of the cultures. The same serum, 

 however, failed to agglutinate cultures of B. coli, isolated 

 from the stools of other children fed under the same con- 

 ditions. The action of anti-typhoid serum on B. coli will 

 be fully considered when the value of the agglutination 

 test for the diagnosis of the B. typhosus is discussed. Here 

 it will be sufficient to state that though many varieties of 

 B. coli are quite uninfluenced by anti-typhoid serum, still races 

 do occur which are agglutinated by anti-typhoid serum in 

 low dilutions. The virulence of the B. coli does not appear 

 to have any relation to the action of the anti-typhoid serum 

 upon it. Jatta passed cultures of the B. coli through guinea- 

 pigs, so as to increase their virulence ; the test serum, however, 

 acted on the organisms in just the same manner after the 

 treatment as before it. It has also been found that a coli-serum 

 from an immunised animal sometimes causes agglutination of 

 the B. typhosus, but the dilution which produces the agglutina- 

 tion is always much lower than that which acts on the culture 

 of B. coli used to produce the serum. It also appears that 

 those varieties of B. coli, which are influenced by anti- typhoid 

 serum, produce, when injected into animals, sera which act on 

 the B. typhosus. 



The Bacterium lactis aerogenes, the Bacillus cavicida, the 

 Bacterium tholceidum, and the Bacillus Neapolitans, isolated 

 from fasces, appear to be closely allied to the B. coli. 



The Bacterium Lactis Aerogenes was isolated by Escherich 

 from the intestinal tract of animals and people fed on milk, 

 and especially from suckling children. It was found once in 

 raw milk. In gelatine plates the surface colonies are convex, 



