VACCINE-THERAPY 65 



tubule each containing the patient's serum ; (6) control 

 serum; (c) the washed emulsion of leucocytes; (d) the 

 emulsion of bacteria. 



We then take up a pipette and immerse the point into 

 the emulsion (bacterial), and draw up by relaxing the 

 rubber teat one volume — i.e., up to the grease pencil mark 

 — withdraw the point from the emulsion, and slightly 

 relaxing the pressure upon the teat, allow the ingress of a 

 column of air. In like manner take up one volume of 

 leucocytic emulsion, and then a column of air. Dip the 

 pipette into the leucocytic emulsion again and take up 

 another volume, then a column of air, and lastly draw up 



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Fig. 31.— A, Pipette with Rueber Teat containing in Order 

 the Individual Elements separated by Columns of Air ; 

 B, Pipette showing the Elements thoroughly mixed and 



READY FOR INCUBATING. 



one volume of serum. In the pipette we now have, count- 

 ing from the point to the teat, a volume of serum, a column 

 of air, a volume of leucocytes, a column of air, a volume of 

 leucocytes, a column of air, a volume of emulsion. The 

 operator having laid out a clean slide in front of him, the 

 point of the pipette is made to rest upon it, and the fluid in 

 the stem expelled and sucked up several times to thoroughly 

 mix the contents. 



It may be well to note here that the teat should perfectly 

 fit the stem of the glass, failing which we will not obtain 

 the same free aspirating and expelling powers we should 

 have. This point can be proved by pressing the teat, and 

 then sealing the end. If the union is complete, the teat 



5 



