240 IMPORTANT VARIETIES OF FISSION-FUNGI. 



coli. (2) The delicate growth upon potato, since there are typhoid 

 bacteria which grow as luxuriantly as Bact. coli. In order that a 

 potato culture may be of diagnostic value, two pieces from the same 

 potato must be placed in a dish and inoculated, one with the culture 

 in question, the other with a certain typhoid culture (Germano and 

 Maurea). According to these authors, with whom Lb'sener agrees, a 

 deviation from the growth of true typhoid bacteria upon the same 

 potato is sufficient to exclude a diagnosis of typhoid. (3) Growth upon 

 nutrient media to which are added antiseptic substances (phenol, form- 

 aldehyd, acids, etc.). The Bact. coli always tolerates these somewhat 

 better than the typhoid bacterium. 



The Diagnosis of Bacterium typhi is excluded : 



If one of the following properties is demonstrated: 



1. Absence of motility, flagella absent or located at the 

 pole, typical spores, staining by Gram's method. 



2. Absence of growth at body temperature. 



3. Coagulation of milk. Formation of gas in grape- 

 sugar agar or fermentation tubes. 



4. Liquefaction of gelatin. 



A beautiful example of a thorough differential diagnosis 

 between mud and typhoid bacteria is given by Houston 

 (C. B. xxiv, 518). 



Serum Diagnosis of Typhoid. 1 



In doubtful cases the typhoid diagnosis may very often 

 be verified by the serum test. Since we have been 

 acquainted with the Gruber-Durham agglutination reaction 

 in vitro, almost always this is employed instead of R. 

 Pfeiffer's more detailed reaction in the abdominal cavity 

 of the guinea-pig. Cultures upon slanted agar, eighteen 

 to twenty-four hours old at 37, are used for the test, and 



1 If one has no immune serum, still, according to Laschtschenko, 

 he may differentiate the Bact. typhi from the Bact. coli in the follow- 

 ing manner (H. R. , 1899, No. 3): Several test-tubes, each containing 

 2 c.c. of fresh defibrinated rabbit's blood, obtained by venesection, are 

 provided. To these are added tvwo drops of a dilute suspension of the 

 culture in question. The suspension is prepared by mixing 1 loop- 

 ful of an agar culture with 10 c.c. of bouillon, and then diluting 0.5 

 c.c. of this with 9.5 c.c. of bouillon. In the case of Bact. coli which 

 have not been cultivated too long, the bacteria are never dead in 

 six to seven hours, and usually are much more numerous, while 

 the Bact. typhi (ten cultures!) were always much less in number, 

 no matter whether the culture had been isolated for a short or long 

 time. 



