OPSONINS IN TUBERCULOSIS 293 



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 milligramme) given at fairly long intervals (say ten 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 experi- 

 mental error of the opsonic method have been sufficiently defined. 



Great controversy has taken place as to whether it is justi- 

 fiable, in the treatment of tubercular cases with tuberculin, 

 merely to rely on the observation of the clinical effects, with- 

 out having recourse to the constant estimation of the opsonic 

 index, which Wright considers advisable. There is no doubt 

 that in all complicated cases of tuberculosis, such as lung 

 affections and cases of multiple foci in the body, the treatment 

 ought to be in the hands of an expert. In cases of strictly 

 localised tubercle, however, such as adenitis, arthritis, cystitis, 

 or lupus, Wright admits that in many cases, without much 

 risk, an uncontrolled treatment may be undertaken. The 

 injections ought to begin with doses of one-twenty-thousandth 

 of a milligramme, with ten-day intervals intervening between 

 each dose. If clinical improvement occurs, the dose may be 

 gradually increased until it- reaches one four-thousandth of a 

 milligramme after six months. If the treatment of any other 

 form of tuberculosis be undertaken along similar lines, the pre- 

 liminary injection should not consist of more than one-fifty- 

 thousandth of a milligramme. 



The whole question of the immunisation treatment of tuber- 

 culosis 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 true 

 not only of man but of many species of animals used in experi- 

 mental inquiries, that many individuals are on the border-line 

 between immunity and susceptibility. From the widespread 

 distribution of the bacilli in centres of human population, it is 

 certain that the opportunity for infection arises in a very large 

 proportion of the race ; in many cases no results follow infection, 

 and in many others small lesions occur which do not develop 

 further ; this has actually been shown by morbid anatomists to be 

 the case. The disease being thus so often characterised by transient 



