234 



APPLIED IMMUNOLOGY 



in an agate mortar and suspended in 0.85 per cent, 

 solution of sodium chloride. After fixation of the 

 smears either by ethyl or methyl alcohol or by heat, 

 the usual staining method comprising carbol-fuchsin, 

 nitric acid and methylene blue for tubercle bacilli is 

 employed (see Frontispiece). The number of bac- 



FiG. 31. — Kuhnhardt'3 spreader properly held at the right angle for the preparation of 

 a satiafactory smear. 



teria contained in no fewer than one hundred phag- 

 ocytes should be counted and the index determined as 

 noted above; or, in accordance with the method of 

 Simon, the ratio of the number of phagocji:ing leuco- 

 cytes may be determined. The latter method is 

 simpler, less exacting on vision and possibly just as 

 reliable as the method of Wright. 



