344 INFECTION AND RESISTANCE 



The first question has, in part, been answered in the preceding 

 paragraphs. Reasonably accurate comparative estimations of the 

 opsonic properties of serum can unquestionably be made by Wright's 

 method, or some of its accepted modifications, in the hands of trained 

 workers who look upon each estimation as an experimental problem 

 and have time for control and repetition. That even in such cases 

 the matter is difficult is amply testified to by such reports as that of 

 E. C. Hort, 27 who states that two of the most skilled experts 28 in 

 London, working with samples of the same serum taken before and 

 after vaccination, reported "the one that the index was raised, the 

 other that it was lowered by the treatment." This, and similar ex- 

 periments of other observers, do not, of course, invalidate the results 

 obtained in special researches like those of Wright, Neufeld, and 

 others, but they do indicate that the control of clinical cases by 

 opsonic estimations is not a matter that can profitably be made a 

 routine procedure by which the treatment of the cases can be regu- 

 lated. As a problem of clinical research in a given series of patients 

 opsonin studies are unquestionably valuable and the comparative data 

 so obtained have proved, and will continue to prove, of great value. 

 But we cannot hope as yet, it seems to us, to utilize this method, ex- 

 cept in cases in which much time and care can be centered upon a 

 few patients under the best conditions. Opinions essentially similar 

 to this have been expressed by experienced clinicians (Potter, 29 for 

 instance), who have followed out series of cases on which systematic 

 opsonin determinations were made. 



As to the opsonic index in tuberculosis, we believe that the ex- 

 perimental evidence at present available does not show that such 

 measurements are reliable measures of resistance, and, in this dis- 

 ease, even when the index is taken with a degree of care which 

 precludes gross error, it is doubtful whether its estimation is of as- 

 much value in controlling treatment as are the data obtained by 

 skilled clinical observation. 



This leaves us, therefore, for the control of vaccine treatment in 

 the routine work of the clinic only the information gleaned from 

 such indications as alterations in any visible or palpable lesions, 

 general systemic symptoms, temperature, leukocytosis, etc. Since 

 these will present such manifold and variable pictures in different 

 conditions, generalization is useless. 



The second question concerning the value of vaccine treatment 

 in infectious disease of human beings cannot be so briefly answered, 

 and is one of the greatest importance in medicine. It is well known 



27 Hort. Br. Med. Jour., Feb., 1909, p. 400. 



28 Quoted from Adami, Trans. Amer. Phys. & Surg., Vol. 8, 1910. See- 

 also Pearson, Biometrica, 1911. 



29 Potter. Loc. cit. 



