CHAPTER IV. 



CRITICISMS AND MODIFICATIONS 



OF WRIGHT'S OPSONIC INDEX 



DETERMINATIONS 



Wright's publications on opsonins, the part they play in im- 

 munity and the method of determination of the opsonic index 

 lead to much investigation on these subjects. Many investiga- 

 tors followed Wright's methods closely while some have followed 

 what they supposed were Wright's methods. The first reports 

 of work done by investigators other than Wright and his pupils, 

 agree strikingly with the results obtained by Wright. Later 

 results, however, were not as favorable either before or after 

 Wright himself and some of his pupils had demonstrated and 

 taught his technique. For a time want of personal skill and 

 ability, improper methods of work, and lack of ability to manipu- 

 late were supposed to account for results which did not agree 

 with those obtained by Wright. Numerous investigators, how- 

 ever, after having received instructions from Wright and his 

 pupils on the methods of determining the opsonic index, seriously 

 questioned the methods of Wright. This list of investigators 

 includes Park, Simon, Baldwin, Cole, Moss, Potter, Bolduan, 

 Walker, and many others. On the other hand there are num- 

 erous investigators who have not questioned the technique and the 

 results obtained by following the methods of Wright. These 

 investigators followed principally the opsonic index in the various 

 bacterial diseases and made efforts to determine the nature of 

 opsonins, their importance and behavior in the various diseases. 



The opsonic index, according to Wright, is obtained when 

 the average number of bacteria ingested per leucocyte in a mix- 

 ture of patient's serum, bacterial emuslion and leucocytes in- 

 cubated for a certain period of time, is divided by the average 



