PATHOGENIC BACTERIA. 101 



ner, the diphtheria bacillus, then gains entrance and the disease 

 develops. 



Products. But it is not the mere presence of the bacillus that 

 gives rise to all trouble ; certain products which they generate 

 get into the system and produce the severe constitutional symp- 

 toms. 



Eoux and Yersin, in 1888, discovered that the injection of the 

 filtered culture bouillon (that is, freed of all diphtheria bacilli) 

 gave rise to the same palsies as when the bacilli themselves were 

 introduced. 



Brieger and Frankel, through frequent precipitation of the 

 culture bouillon with acetic acid and alcohol, obtained a white, 

 amorphous body, which gave all the reactions of an albumen, 

 and being highly toxic, they gave it the name of tox-albumen. 

 It is soluble in water and decomposed by higher temperatures. 



Immunity. Brieger and Frankel, by injecting 10 to 20 c.cm. 

 of a three weeks' old culture of diphtheria bacilli, which had 

 been heated at 70 C. for one hour, produced an immunity in 

 guinea-pigs against the virulent form. 



Behring found several ways to make animals immune. One 

 method was to infect them with diphtheria and then inject tri- 

 chloriodine into them, which prevented them from dying, and 

 they were then immune. 



Site of Bacilli. Bacilli are usually found in the older portions 

 of the pseudo-membrane very near to the surface. The secre- 

 tions of the throat of a diphtheritic child produced bacilli three 

 weeks after the temperature was down to normal. 



Streptococcus in Diphtheria. Streptococci have been found 

 quite constant in diphtheria, but they resemble the strepto- 

 coccus pyogenes, and have no specific action. 



Bacillus of Typhoid or Enteric Fever. (E berth-Gaff ky.) 



Origin. Eberth found this bacillus in the spleen and lym- 

 phatic glands in the year 1880, and Gaff ky isolated and cultivated 

 the same four years later. 



Form. Rods with rounded ends about three times as long as 

 they are broad. Usually solitary in tissue-sections, but in arti- 

 ficial cultures found in long threads. Flagella on the side. 



Properties. They are very motile ; they take the aniline dyes 



