132 PRACTICAL METHODS IN IMMUNITY. 



bation for the patient's blood and the same time for the control blood, 

 file off the sealed tip, cautiously eject the contents on a slide, and after 

 mixing, spread a film on a slide or cover-glass. Fix with burning 

 alcohol and stain with formoi fuchsin. With Wright's stain the 

 dark nucleus obscures some of the bacteria. Counting the phago- 

 cytized bacteria in a given number of polymorphonuclears, we obtain 

 an average number of bacteria phagccytized per cell. Repeating the 

 count with the control or normal blood, we likewise have the average 

 number of bacteria taken up per cell. Dividing the patient's average 

 by the normal average, we have the opsonic index. If the average for 

 50 of the patient's cells was 8 and that of the control only 4, the patient's 

 index would be 2, or twice the normal. The practical value of this 

 test is where 2 or more organisms are in a body fluid we may ascertain 

 the causative organism by noting marked variation from the normal in 

 the patient's opsonic index for that particular organism and not for the 

 other organism. This variation may be of the nature of a high or low 

 opsonic index. 



Preparation of Vaccines. It has been found satisfactory 

 to make use of stock vaccines in gonorrhceal and tuberculous affections. 

 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 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. Having isolated the organism, it is 

 inoculated upon one or more agar slants, and after a growth of from 

 5 to 7 hours with streptococci and pneumococci, or with 18 hours for 

 staphylococci and colon, the growth on these inoculated slants is 

 taken up with salt solution, thoroughly shaken up in the diluting solu- 

 tion and standardized. 



The most practical way is to gently rub off the growth on the agar 

 in about i or 2 c.c. of salt solution with a platinum loop. Then pour 

 the bacterial emulsion into a sterile test-tube and repeat the process 

 with 3 to 5 agar slants, until we have from 6 to 10 c.c. of the emulsion 

 in the sterile test-tube. By heating to melting-point in the flame a piece 

 of glass rod and attaching it to the rim of the test-tube (also melted), 



