TYPHOID FEVER. 175 



exhibit, or have exhibited, the clinical symptoms of typhoid 

 fever. 



Recent and reliable aids in the differential diagnosis 

 between the bacillus of Eberth-Gaff ky and the great horde 

 of bacteria resembling the typhoid-bacillus and the bac- 

 terium coli are furnished by the reaction of Pfeiffer and 

 that of Gruber. (See General Section, pp. 62 and 63.) 

 Ten times the minimal lethal dose amount of the sus- 

 pected bacteria are mixed with a small amount less than 

 O. I cu. cm. of serum obtained from an animal highly im- 

 munized against typhoid fever, and the mixture is injected 

 into the peritoneum of a guinea-pig. If after from ten to 

 twenty minutes the characteristic disintegration of the bac- 

 teria into granules becomes apparent in the fluid obtained 

 from the abdominal cavity by means of a capillary tube, 

 the conclusion may be reached that the organisms are 

 actually typhoid-bacilli. If the virulence of the microor- 

 ganisms is slight or wanting, Pfeiffer' s reaction is obviously 

 not available. Under these conditions Gruber' s reaction is 

 employed. The technic has been described in the general 

 section (p. 64). If agglutination takes place, the diagnosis 

 may be considered as positive. 



Typhoid-bacilli are isolable from the feces only with 

 great difficulty on account of their close resemblance to 

 the bacterium coli commune. The procedure most likely 

 to prove successful is that recommended by Eisner. 

 Plates are made in the usual manner with potato-gelatin 

 (see Methods of Culture and of Examination, p. 81), to which 

 shortly before use potassium iodid has been added in the pro- 

 portion of one per cent. This culture-medium appears espe- 

 cially adapted for the growth of typhoid-bacilli and coli-bac- 

 teria, with the qualification that the latter grow more vigor- 

 ously than the former. After the lapse of forty-eight 

 hours the colonies of coli-bacilli appear as dark-brown 

 spherical masses, while those of the typhoid-bacilli appear 

 as small, transparent, water-like, drops. The method of 

 Eisner is, however, not absolutely trustworthy. Its appli- 

 cation requires much practice, and it does not render 

 superfluous further precise identification of the apparent 

 typhoid-colonies according to all of the rules mentioned. 



The bacteriologic diagnosis of typhoid fever may be 

 made quickly and easily by puncture of the spleen, and the 

 development of cultures from the fluid obtained. If the 



