SCIENCE IN MEDICINE 257 



Were this method combined with the inoculation of bacterial 

 vaccines, and a blood rich in protective substances brought to 

 the site of infection, its value should be considerably increased. 

 There are, therefore, at our disposal many methods of drawing 

 blood to the surface, and thereby concentrating its anti-bacterial 

 properties on local bacterial infections in these parts. In the 

 case where after operation a sinus has formed, and the wound is 

 not completely healed, the situation is probably as follows : the 

 walls of such a sinus consist of coagulated lymph, which 

 furnishes a splendid medium for bacteria to grow on ; moreover, 

 this clot is almost without blood supply, so that the bacteria 

 meet with little opposition. Antiseptics are used to wash it out 

 frequently and to plug it, but unless every single bacterium be 

 killed, in a few hours there are thousands more. Wright has 

 suggested that if a solution of sodium citrate (1*5 per cent.) is 

 introduced into the sinus, the coagulum of lymph is dissolved ; 

 and if to this a solution of dextrose (12 per cent.) is added, 

 serum will be drawn through the wall of the sinus by a process 

 of osmosis, and thus the anti-bacterial properties of the blood 

 can be utilised. This is a scientific application of another very 

 old household remedy, the outcome presumably of accident or 

 instinct and long experience — namely, the soap and sugar 

 poultice, 1 the soap exerting the same decalcifying action on the 

 blood as the citrate, and the sugar "drawing" the lymph to the 

 surface. 



Sero-diagnosis. — It will also be understood from what has 

 been said that the examination of the blood, as regards its 

 opsonic power, may be used not only as a guide in treatment, 

 but as an aid in diagnosis. This means of diagnosis — com- 

 parable to the Widal test now so well known in clinical 

 medicine — has already been fully investigated as regards the 

 diagnosis of Tubercle. 2 The following are the main results 

 obtained in this research. 



1. If the opsonic index of a patient suffering from a local 

 bacterial infection which suggests tuberculosis is persistently 

 low to the tubercle bacillus, the lesion in question may be taken 

 to be of a tubercular nature. 



2. If on a single examination of the blood the opsonic index 

 is found to be high, and on a succession of examinations is found 

 to be continually fluctuating, then, if the patient is suffering from 



1 Med. Chi. Trans., vol. 89. 2 Proc. Roy. Soc, 1906. 



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