

OPSONINS AND VACCINE THERAPY 341 



the end is sealed; and incubation at 37.5 is carried on for an 

 arbitrary time, usually fifteen to thirty minutes. 19 The control with 

 normal serum is treated in exactly the same way. After incubation 

 the end of the pipette is broken off, the contents are again mixed, 

 and smears are made upon glass slides in the ordinary manner of 

 blood smearing. Staining may be done by .Wright's modification 

 of Irishman's stain, by Jcnner's, or by any other of the usual blood 

 stains. In these smears, then, the number of bacteria contained in 

 each leucocyte is counted. The contents of about eighty to one 

 hundred cells are usually counted and an average is taken. This 

 average number of bacteria in such leucocytes is spoken of as the 

 "phagocytic index." The phagocytic index of the tested serum, 

 divided by that of the " normal pool" (control) serum, gives the 

 "opsonic index." 



Another method of estimating the opsonic content of a given 

 blood serum has been contributed by Simon, Lamar, and Bispham. 20 

 These authors employed dilutions both of the patient's serum and 

 of normal serum ranging from one in ten to one in one hundred. 

 With these dilutions, they carry out opsonic experiments with bac- 

 terial emulsions and washed leucocytes in the same way as this is 

 done in the Wright method, except that they recommend the employ- 

 ment of thinner bacterial emulsions than are usually employed in 

 the former method. In examining their slides, they do not estimate 

 the number of bacteria found within the leucocytes, but rather the 

 percentage of leucocytes which actually take part in the phagocytic 

 process, 21 i.e., which contain bacteria. 



By the same method of dilution, they determine what they have 

 called "the opsonic coefficient of extinction," a phrase which is used 

 to express the degree of dilution of the serum at which no further 

 phagocytosis takes place. They claim for their methods the more 

 delicate determination of variations in opsonic power. The method 

 has not been sufficiently used to permit the expression of an opinion 

 as to its value. 



The Vaccine Therapy of Wright. In connection with his more 

 theoretical work upon opsonins, Wright has laid much stress upon 



19 For the purpose of incubation, specially constructed water baths, marketed 

 under the name of "opsonizers, " may be used. 



Simon, Lamar, and Bispltam, Jour. Exp. Med., viii, 1906. 

 21 Simon and Lamar, Johns Hopkins Hosp. Bull., xvii, 1906. 



