BACTERIAL VACCINES 159 



to break up clumps repeated suction and ejection with a capillary pipette provided 

 with a rubber nipple is satisfactory. 



The presence of clumps in a bacterial emulsion invalidates the estimation of 

 phagocytosis, for the reason that a leukocyte will take up a clump of twenty or more 

 bacilli as readily as one separate organism. 



Having at hand (i) the suspension of leukocytes, (2) the bacterial emulsion, 

 and (3) the sera of the patient and the normal individual, we are ready to proceed 

 with the test. 



Using a capillary bulb pipette with a pencil mark to indicate i volume we draw 

 up to the mark (i) the leukocyte cream. Then wiping off the tip of the pipette we 

 draw up this volume of leukocyte emulsion about one-half an inch to make an air 

 break between this and (2) i volume of the bacillary emulsion. Again making an 

 air space we draw up (3) the serum of the normal individual. This gives 3 columns in 

 the capillary tube with intervening breaks of air. We next eject the three con- 

 stituents into a watch-glass and thoroughly mix them by alternate suction and ejec- 

 tion with the tube and nipple. When mixed we draw the mixture up into the same 

 capillary tube, seal off the capillary end in the flame and put in an incubator for 

 exactly 15 minutes. 



We next repeat the process identically except that the patient's serum is used in- 

 stead of that of the normal individual. 



These tubes having been kept at the same temperature for the same length of 

 time are then taken out, the contents blown into a watch glass, mixed thoroughly 

 a second time, and then a smear is made a drop of the mixture being deposited 

 on a very clean slide and the smear made by a second narrower slide (by cutting off 

 the corner of the slide) which is drawn along in a zigzag way. The smears are then 

 stained (Leishman's or Wright's blood stain or Ziehl-Neelson's for tubercle bacilli) 

 and the number of the bacteria in from fifty to one hundred leukocytes counted. 

 This number divided by the number of cells gives the phagocytic average. 



The phagocytic average of the patient's tube divided by that of the normal in- 

 dividual's tube gives the opsonic index. Thus,, in counting 100 cells we find 500 

 phagocytized cocci in the patient's tube, giving an average of 5, and in the normal 

 individuals blood we get 1000, an average of 10. Then the opsonic index would 

 be 5 -Mo, or 0.5. 



PREPARATION OF VACCINES. 



It has been found satisfactory to make use of stock vaccines in 

 gonorrhceal and tuberculous affections. In treatment of tuberculosis 

 Wright prefers Koch's T. R. or Neu Tuberculin in doses of from 1/5000 

 to 1/800 of a milligram. Some prefer Koch's more recent bazillen 

 emulsion. In case of other infections, however, and preferably with 

 gonorrhceal infections, the causative organism should be isolated from 

 pus, sputum, urine, blood, or other material (autogenous vaccine). 



In the making of vaccines all media and 'apparatus should be sterilized with 

 scrupulous care to avoid the danger of tetanus infection. Having isolated the organ- 



