1904.] the Tubercle Bacillus ly Human Blood Fluids, etc. 171 



capable of inducing an elaboration of tuberculotropic substances in the 

 organism. 



We may include under this definition : 



(1) Such a vaccine as would be arrived at by (a) sterilising a 

 tubercle culture at 60 C. ; (b) breaking up the culture in a mortar in 

 0-1-per-cent. salt solution ; (c) centrifugalising to remove any residual 

 bacterial masses ; (d) resterilising at 60 C. ; and (c) standardising by 

 enumeration, or by centrifugalisation in graduated tubes in a sufficiently 

 concentrated salt solution. 



(2) The preparation, which is sold, as a therapeutic agent, under the 

 name of Koch's new tuberculin or T.R. tuberculin. 



This preparation consists, as is well known, of a fine suspension of 

 triturated tubercle bacilli. The trituratiori to which the tubercle 

 culture is subjected is employed with the two-fold object of sterilising 

 the vaccine by a process of comminution, and of obtaining the fine 

 suspension which is desired. 



It is doubtful whether the first of these ends can be efficiently 

 secured by any process of trituration. The homogeneous suspension 

 which is desired can, as was shown above, be obtained by means other 

 than the comminution of the bacilli by machinery. 



(3) The preparation, which is now sold, chiefly for diagnostic uses, 

 under the name of Koch's old tuberculin.* 



This preparation consists, as is well known, of the inspissated filtrate 

 of a tubercle culture which has been grown for a period of weeks upon 

 glycerinated broth, and which has afterwards been sterilised at 100 C. 



Pending the working out of a vaccine upon the lines indicated in 

 (1), the T.R. tuberculin has been the vaccinating material employed. 



In our earlier experiments this preparation was simply diluted with 

 sterilised salt solution. 



In our later experiments we have after satisfying ourselves that 

 the vaccinal properties of Koch's preparation are unaffected by the 

 adoption of such precautions in every case heated the T.R. tuberculin 

 to 60 C. for 1 hour, and have made our dilutions with a sterilised 

 salt solution which had received an addition of O25 per cent, lysol. 



* The proposition that the old tuberculin may appropriately be denoted a 

 vaccine derives its justification, first, from the consideration that the prolonged 

 cultivation and the prolonged digestion of the culture which is involved in the 

 process of manufacture must be associated with autolysis, and secondly, from 

 the observations made in connection with Case 13 of Table I and the last patient 

 in Table III. 



In the former case, the opsonic index of the patient's blood stood at O56 

 immediately before the inoculation of 1 millegramme old tuberculin. It stood at 

 0'55 18 hours afterwards in the height of the febrile reaction, and at I'Ol 3 days 

 later. 



In the latter case, the opsonic index of the blood stood at 0'67 immediately 

 before the inoculation of 1 millegramme of the old tuberculin. It stood next day 

 at 0'4, and 8 dajs later at 0'76. 



