SERUM DIAGNOSIS OP TYPHOID. 45 



this test, an 18 to 24 hour broth culture, or suspension, 

 of moderately virulent Typhoid bacilli, and certain 

 dilutions of the serum used, are required. 



A dilution of at least 1 part of serum in 30 is neces- 

 sary. The time limit for the reaction should be set at 

 2 hours. Usually the phenomena are noted within a 

 few minutes. 



Blood, from a fatal case of Typhoid fever, dried on 

 sterile thin filter sheets and cut into squares of 1 cc. is 

 furnished. (Blood may also be preserved in standardized 

 capillary pipettes) . 



4. With sterile forceps place a dried blood square 

 in a sterile glass capsule. With a medicine dropper 

 carefully add 15 drops of sterile distilled water, so as 

 to extract the agglutinating constituents. 



On a sterile cover glass place one drop of this ex- 

 tract, and add one drop of the 18 hour broth culture of 

 Bacillus typhosus furnished. This makes a dilution of 

 about 1 in 30. 



Examine in hanging drop, under the microscope, and 

 note the characteristic reaction. 



5. Repeat this procedure, using 1 drop of the extract 

 to 3 drops of the broth culture of Bacillus typhosus, giv- 

 ing a dilution of about 1 in 60. Examine as before and 

 note results. 



6. Repeat this procedure using 1 drop of the extract, 

 and 1 drop of a broth culture of Bacillus coli communis. 

 No clumping occurs. 



For clinical examination in cases of Typhoid fever, 

 blood may be taken from the lobe of the ear or the fin- 



