STANDARD AGGLUTINATION 431 



tubes one larger dilution tube on the left-hand side and 15 

 smaller agglutination tubes in three rows of 5 each a dropping 

 pipette with teat and a supply of standard agglutinable cultures 

 of typhoid and paratyphoid A and B (obtainable from the Depart- 

 ment of Pathology, University of Oxford). The following are the 

 directions issued : 



1. TECHNIQUE. 



Take a stand containing 15 agglutination tubes in three rows of 

 5 each, and a dilution tube. 



With the proper dropping pipette measure out into the dilution 

 tube 54 drops of normal saline solution, 0-85 per cent, sodium 

 chloride, in distilled water (where the water supply is pure, tap- 

 water can be used instead of saline solution) by means of gentle 

 pressure on the teat. 



Wash the pipette with distilled water. 



Rinse the pipette with successive quantities of absolute alcohol 

 and of ether, and dry by gentle warming. 



Take up the serum to be tested into the dried pipette. Measure 

 out 6 drops of the serum into the dilution tube already containing 

 the 54 drops of saline solution, thus obtaining a dilution of 1 in 

 10. Mix thoroughly. 



Carefully wash out the pipette. 



With the pipette measure out into each row of tubes as follows : 



Drops of Drops of 



Normal Serum 



Number Saline Dilution 



of tube. Solution. 1 in 10. 



1 10 to each tube in row 1 add 15 drops of 



B. Typhosus Standard Agglutinable 



Culture. 



. to each tube in row 2 add 15 drops of 

 \B. Paratyphosus A. Standard Agglu- 

 tinable Culture. 



to each tube in row 3 add 15 drops of 

 B. Paratyphosus B. Standard Agglu- 

 10 / tinable Culture. 



At each stage of the procedure the pipette is carefully washed 

 and dried out as before described. 



Shake each tube thoroughly in order from right to left, i.e. 

 beginning each row with the highest dilution. 



Place the stand for two hours in a water-bath at 50-55 C. (not 

 in dry air). 



