56 VACCINE AND SERUM THERAPY. 



The indices in individual cases are so variable and show such great 

 irregularity that determinations of the opsonic index in any case 

 give little indication of the severity of the disease and is of no 

 value in prognosis. 



Most investigators have found that in normal individuals 

 the curve of opsonic index is very irregular. Moss in thirteen 

 observations on one individual determined indices which varied 

 from 0.52 to 1.95 and in another from 0.42 to 1.66. Bolduan 

 reports observations in which one patient's serum varied in opsonin 

 content as determined by Wright's opsonic index from 0.82 to 

 2 . 50 in seventeen days. Inasmuch as the opsonic index during 

 infections shows no greater variation than during health it can 

 hardly be accepted that determinations of opsonic indices are of 

 much assistance in diagnosis and prognosis in disease. 



Up to the present, most investigators have found that in the 

 natural course of infection there is no regular curve of the opsonic 

 index and that in the natural recovery from an infection the 

 changes in opsonic index are not those which Wright attempts 

 to obtain by injection of killed cultures of bacteria. 



CHANGES IN OPSONIC INDEX PRODUCED BY INJEC- 

 TIONS OF KILLED CULTURES. 



Wright has observed that the injection of killed cultures is 

 usually followed by a change in opsonic index for the organ- 

 isms injected. If the amount of killed cultures injected is large, 

 he states there is a marked negative phase, after which there 

 may be either a marked or slight increase in the opsonic index. 

 If the amount of killed cultures injected is small, the negative 

 phase may be small or absent entirely and following this there 

 may or may not be a positive phase. Wright has attempted to 

 regulate injection of killed cultures so as to get as small a nega- 

 tive phase and as large a positive phase as is possible. To accom- 

 plish this, he has determined the number of killed cultures in emul- 

 sions and has injected certain numbers of bacteria at a dose, the 

 number varying with the species of the organism and the opsonic 

 index changes obtained by their injection. In some cases Wright 

 has resorted to autoinoculation, which is accomplished by mas- 

 sage or manipulation of the infected part. This partly removes 



