VACCINE THERAPY AND THE OPSONIC INDEX 213 



study has proved that such parallelism exists. This fact is probably 

 correct in the majority of instances, but it cannot be considered as an infal- 

 lible rule, inasmuch as the formation of opsonins is only. one of a great 

 number of factors in the complicated process of healing; consequently one 

 should not be surprised when in some instances in spite of a rising opsonic 

 index, the patient's clinical condition becomes worse, and reversely when 

 in some cases improvement occurs although the opsonic index does not 

 change. 



Accordingly, the opsonic index during the course of treatment becomes 

 secondary in importance to the exact clinical observation of the case. 

 Wright and his school have shown that certain bad effects may follow 

 from the injection when performed during the negative phase. With 

 the use of small doses the negative phase becomes short only one 

 day or even less; accordingly it is very probable that this state is entirely 

 passed when an injection is repeated on the fifth to eighth day. 



The tuberculin therapy at the Kraus clinic is conducted on this principle, 

 without estimation of the opsonic index. And yet, no harmful effects have 

 ever been noted; while general improvement, as increase in weight, diminu- 

 tion in temperature and cessation of cough, are constantly observed. It 

 would be illogical to neglect these clinical data and give preference to the 

 hypothetical action of opsonins as a guide in treatment. 



It seems that Wright himself does not insist as strongly as before upon 

 the determination of the opsonic index. One of his assistants, Matthews, 

 has made the statement that in a great number of cases the determina- 

 tion of the opsonic index is entirely out of the question. If the choice 

 between injections without estimation of the index and entire omission of 

 inoculation should arise, therapeutic inoculation without the index is by all 

 means indicated. There is a general tendency at present to omit the 

 opsonic index in the treatment of staphylococcus infections, and this is 

 at times also done in tubercle, gonococcus and streptococcus infections as 

 well as in prophylactic typhoid inoculations. 



Neufeld's Method of Bacteriotropin Estimation. 



Neuf eld's technique varies from that of Wright in two points: 



(1) He uses serum free of complement. 



(2) He does not count the number of bacteria within the leucocytes; 

 but makes various dilutions of the serum and notes in which dilution the 

 bacteria are still ingested in great numbers, as compared with a normal 

 serum in similar dilution as control. 



Neufeld usually obtains the leucocytes by injecting a guinea-pig intra- 

 peritoneally 1 6 to 24 hours previously with 5 to 10 c.cm. of sterile aleuronat 

 solution (i part aleuronat, 2 parts bouillon). It is best to kill the guinea- 

 pig, and wash out the peritoneal exudate which is full of leucocytes with 



