PARATYPHOID. 449 



power of 1 to 160 has often been found at eight 

 months, and of 1 to 50 after from seven and one- 

 half to eleven years; but the latter duration is not 

 the rule. In performing the test, a serum dilution 

 of not les than 1 to 40, or 1 to 50 should be 

 observed as previously set forth. 



The following sources of error are to be borne 

 in mind: Typhoid fever occasionally runs its 

 course without the formation of agglutinins; the 

 reaction may mysteriously be absent one day to 

 recur a few days later, a condition which indicates 

 the importance of repeated tests; rather high ag- 

 glutinating power for the typhoid bacillus occa- 

 sionally develops in other infections, as pneumo- 

 nia, meningitis, icterus, Weil's disease, etc.; the 

 possibility of group agglutination, for the positive 

 elimination of which control tests with related or- 

 ganisms may be demanded. In case negative 

 results are obtained in a suspicious case, the reac- 

 tions should be tried with the paratyphoid bacilli. 

 The test of the bactericidal powers of the serum 

 has been recommended as a substitute for the ag- 

 glutination reaction, but the technic is so much 

 more complicated that the method will probably 

 not come into general use. For diagnosis previous 

 to the formation of agglutinins, blood-cultures 

 should be made as described in a preceding para- 

 graph. 



II. PARATYPHOID FEVER. 



In 1900 Scholtmiiller cultivated from the blood 

 of five "typhoid" patients organisms which differ p ara t y piioid 

 from the typhoid bacillus in that they attack dex- S?jj raco i on 

 trose with gas formation and are not agglutinated Bacim. 

 in high dilution by antityphoid serum. Since 



