198 Dr. A. E. Wright and Staff-Surgeon S. T. Keid. [Oct. 21, 



low after infection has supervened, while it can invariably be raised by 

 appropriate inoculation,* indicates that the machinery of immunisation with 

 which the organism is furnished is not, under the conditions which obtain in 

 strictly localised tubercular infections, spontaneously called into play. 



The constant fluctuation in the opsonic power of the blood in cases of active 

 pulmonary tuberculosis and other active forms of tubercular infection 

 furnishes — as we can hardly doubt — evidence of a periodic conveyance of 

 tubercular elements into the blood ; and of a response to such stimulation on 

 the part of the machinery for immunisation. The low opsonic indices 

 registered in connection with active tuberculosis would in other words be 

 " negative phases " such as supervene — as one of us has shown — upon the 

 inoculation of all vaccines ; the high opsonic indices would be " positive 

 phases," such as normally succeed upon the negative phases just mentioned ; 

 and the normal opsonic indices would correspond to periods of transition 

 between negative and positive phases, Or, as the case may be, to periods 

 in which the blood is returning after a positive phase to the condition quo 

 ante. 



The life of a patient with any really active form of tuberculosis would in 

 conformity with this view be a life of alternating negative and positive 

 phases : the favourable or unfavourable event of the infection being in each 

 case determined by the adjustment or want of adjustment of the auto- 

 inoculations (with respect to dosage and interspacing) with the particular 

 patient's capacity for immunising response. 



Having now to a certain extent cleared the ground, we may pass on to 

 consider the question of the diagnosis of tubercular infection by means of the 

 measurement of the opsonic power of the blood. 



Exploitation of the data Summarised above as an aid in the Diagnosis of 



Tubercular Infection. 



Consideration will make clear that the data obtained by the measurement 

 of the opsonic power in cases of doubtful diagnosis may, when adjudicated 

 upon in the light of the data obtained in connection with undoubted cases of 

 tuberculosis as given above, furnish material for admitting or rejecting the 

 diagnosis of tubercular infection. We may formulate in connection with this 

 matter the following propositions : — 



(1) Conclusions which can be arrived at when we have at disposal the 

 results of a series of measurements. 



(a) Where a series of measurements of the opsonic power of the Mood reveals a 



* Exactly the same statements hold true with regard to the staphylo-opsonic power in 

 localised staphylococcus infections (furunculosis, sycosis, etc.). 



