TYPHOID FEVER 93 



of Pathology, University of Oxford. (They are issued free of charge 

 to naval and military medical officers, on behalf of the Medical 

 Research Committee.) The cultures are standardized, so that 

 all results, whether of one observer at different times, or of different 

 observers, are comparable. The method is a macroscopic one, and 

 is carried out in small test-tubes, and the end-point to be sought 

 for (" Standard Agglutination ") is that in which there is com- 

 plete agglutination of the culture, but no sedimentation, the tubes 

 being examined after they have been incubated at 55 C. for two 

 hours and kept at room temperature for fifteen minutes. (If the 

 water-bath at 55 is not at hand, very fairly comparable results can 

 be obtained by keeping the mixtures at room temperature for 

 twenty-four hours before the reading is made.) Further, arrange- 

 ments can be made for determining the action of the patient's serum 

 on paratyphoid bacilli (A and B) at the same time as typhoid bacilli, 

 a very important thing now that paratyphoid fever is known to be 

 so widely distributed. 



The method is as follows : Take a metal stand (all apparatus 

 necessary can be obtained from Messrs. Baird and Tatlock) and place 

 in it a large tube (at the left end) and fifteen small sedimentation tubes. 



With the dropping pipette, held carefully vertical, drop 54 drops of 

 normal saline into the dilution tube, and into the agglutination tubes 

 normal saline, as in the table : 



10 drops of normal saline. 



o o o o 



o 8 



54 drops 



Next, wash the pipette in distilled water, then in alcohol, and then 

 in ether, blowing air through it from the indiarubber teat or from a 

 spray puffer until it is quite dry. Then take 6 drops of serum, add 

 it to the dilution tube, and mix thoroughly. This will give you a 

 dilution of i in 10. 



Again wash out the pipette very thoroughly in distilled water, and 

 add the dilution of serum to the normal saline in the tubes, so that 

 the quantity is made up in all cases to 10 drops : 



o 



O O O O O 



10 5 2 i o drops of diluted serum. 



O O O O O 



10 5 2 i o 



00000 



Wash the pipette again and add to each tube 15 drops of standard 

 culture, putting typhoid culture in the front row, paratyphoid A in 



