AUTO-INOCULATION 203 



distinct evidence of the existence of an infection the opsonic index remains 

 normal. In such instances, for some reason, the bacteria and their products 

 do not reach the general circulation and therefore no occasion is offered 

 for either an elevation or sinking of the opsonic index. Wright and 

 Freeman were able to show that all active and passive motions of an infected 

 joint, as well as any vascular changes which induce a flow of lymph toward 

 the focus of infection, lead to auto-inoculations, which are manifested in a 

 change of the opsonic index. Such artificial production of auto-inocula- 

 tion can be employed in various forms as a means of diagnosis: thus, in 

 articular rheumatism, massage; in pulmonary tuberculosis, breathing 

 exercises; in laryngeal diseases, loud reading; and in tuberculosis of the 

 lower extremities, active gymnastics will occasion changes in the opsonic 

 curve. 



An example is given in Chart 7. The patient was a woman with a swollen wrist 

 joint. In order to decide whether this was a gonorrheal' or tuberculous process, the 

 opsonic index was taken and found to be 0.94 to 0.97 for the gonococcus and 1.03 to 

 1.35 for the tubercle bacillus. As these figures differed very slightly from the normal, 

 the test was repeated, but this time after Bier's hyperemia had been applied and the 

 forearm placed into warm water for one hour. The opsonic index for the tubercle 

 bacillus remained the same, while that for the gonococcus had undergone marked 

 variations. 



A similar experiment with a woman having tuberculous lymphadenitis is given in 

 Chart 8. 



Wright makes use of these variations of index caused by auto-inocula- 

 tion in determining the prognosis of a case. An infection is only then 

 considered cured when artificial auto-inoculation is no longer possible. 



The Technique for the Determination of the Opsonic Index. 



For the determination of the opsonic index are required, 



1. Serum of the patient. 



2. Serum of the normal individual (as control). 



3. Washed blood cells (Leucocytes). 



4. Bacterial emulsion. 



The blood serum is obtained from the finger tip at the root of the nail. 

 It is most efficacious to first produce a hyperemia of this part by constrict- 

 ing the finger either with a narrow gauze bandage or a small soft rubber 

 tube (the editor has found the latter much more convenient) . The prick is 

 then made with a needle or finely drawn out glass tube. The blood flows 

 spontaneously and is collected into one of Wright's capillary tubes (Fig. 

 19) by approximating the curved end of the latter to the blood (Fig. 18). 

 The straight capillary end of the tube (away from the blood) is then 

 warmed in a small flame and sealed. The tube is laid down flat, and 



