OPSONINS IN TUBERCULOSIS 263 



for constitutional effects to occur in order that a beneficial result 

 may follow. Hence much smaller doses of tuberculin than 

 hitherto are given by him. For ordinary cases with low opsonic 

 index and no evidence of constitutional disturbance, an amount 

 of tuberculin corresponding to from one-thousandth to a six- 

 hundredth of a millegramme of tubercle powder is a sufficient 

 dose, and if any dose seems to produce a pronounced negative 

 phase then a smaller dose ought to be tried at the next inocula- 

 tion. For cases clinically tubercular where the index is about 

 normal, then smaller doses, say, the equivalent of a two- 

 thousandth of a millegramme or less ought to be used, the 

 effect on the index being carefully watched. In any case, the 

 dose which is found to give the highest positive phase is the 

 optimum dose and one which need not necessarily be increased. 

 Cases where there is constitutional disturbance should be as a 

 rule left untreated. 



The general position of Wright and his school is, that it is 

 only by the observation of the opsonic index that the application 

 of the tuberculin treatment can be effectually controlled, 

 deductions based on clinical data, such as absence of interference 

 with pulse rate, temperature, etc., or increase of body weight 

 after an inoculation being unreliable, and further evidence of the 

 unreliability of such tests is brought forward in the fact that, in 

 cases of apparent benefit from sanatorium treatment, the opsonic 

 index may still be very low. With regard to the results 

 obtained, many cases have been brought forward by Wright and 

 others where benefit has followed the putting into practice of the 

 principles enunciated, and there is little doubt that the work 

 done has given a fresh start to the active immunisation method 

 in the treatment of tuberculosis. An outstanding event of 

 Wright's work in this field has been his insistance on the good 

 effects produced by extremely small doses of tuberculin (down to 

 the four-thousandth of a millegramme) given at fairly long inter- 

 vals (say 10 days or more). With regard to the efficacy of the 

 opsonic method as affording an index to the progress of a case 

 it must be recognised that the method is still on its trial, and 

 it is doubtful if even in the work of the most careful observers 

 the limits of the experimental error of the opsonic method have 

 been sufficiently denned. 



The whole question of immunisation against the tubercle 

 bacillus presents many difficulties, and it is the merit of Wright's 

 work that it has shed fresh light on some of these. One great 

 difficulty arises from the great chronicity of the results of the 

 infection in the majority of human cases. It is probably 



