BACTERIAL INOCULATION 225 



prepared. Under such circumstances, notably in 

 gonorrhoea! and tuberculous affections, it is impera- 

 tive that the infecting germ be accurately determined. 

 Moreover, the bacterin should be polyvalent, that is, 

 composed of as many different strains of the bac- 

 terium as may be obtainable, and in view of the reports 

 of Besredka, Broughton-Alcock, Ardin-Deltiel, 

 Negre, Raynaud, Gordon, Boinet, Cruveillier and 

 others, it would appear advisable to employ so-called 

 sensitized bacterins. 



Clinical Symptoms versus Opsonic Indeos in Con- 

 trol of Treatment, — Regulation of the size of doses of 

 bacterins and the spacing of the intervals between in- 

 oculations is possible by observations of the clinical 

 symptoms, subjective and objective, and by determi- 

 nations of the opsonic index. Both methods involve 

 special knowledge and are not to be undertaken 

 lightly. The former entails the closest kind of ob- 

 servation respecting local, focal and general responses 

 ( see Chapters XVI and XXI ) . Opsonins are not the 

 only antibodies formed after inoculation of an ani- 

 mal, hence the opsonic index, theoretically, cannot 

 measure the full degree of immunity.^ Practically, 

 the opsonic index in the majority of cases runs par- 



* There is no such thing as absolute immunity, however, a fact pointed 

 out by Pasteur years ago, for an animal will contract disease, irrespective 

 of the degree of immunization, provided the dose of infective material is 

 suflBciently large and virulent. 



15 



