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in the Widal reaction we have an easy means of 

 diagnosing typhoid, the application of this test is 

 of tlie greatest service in those cases where the 

 diagnosis of malaria or typhoid remains doubtful. 

 We shall describe briefly how the test is carried out. 

 There is no necessity for specially constructed bulbs 

 or graduated pipettes, as often thought. 



1. Draw out a piece of glass tubing, so as 

 to make a pipette, having a fine end about the 

 diameter of a hypodermic needle. 



2. Collect enough blood to fill the pipette 

 to the height of about half-an-inch. The blood 

 will readily flow in if the pipette is held sloping 

 downwards. Seal off the fine end in a flame. 

 Centrifugalize, if convenient, but abundance of 

 serum can be got without by allowing to clot. 



3. To Dilute the Serum. — Draw out a piece of 

 glass tubing into a long fine filament ; take a 

 piece about six inches long ; make an ink mark 

 about half-an-inch from the end of the tube ; 

 insert this marked end into the tube containing 

 serum (and clot) and allow serum to flow up to 

 the ink mark ; then let a distinct bubble of air 

 follow (the size of this bubble does not signify) ; 

 next allow broth to flow up to ink mark ; repeat 

 this procedure until nine drops of broth are in the 

 tube ; these are now each separated by an air 

 bubble, and also by a bubble frorh the serum. 

 The dilution is now one in ten. 



Blow out all the drops on to a slide or watch 

 glass, and mix by sucking up and blowing out a 

 few times. 



4. Take a drop of the diluted serum in a 

 fresh piece of tubing, make a mark as before, and 

 then allow broth to flow up ; this gives a dilution 



