TUBERCULOSIS. 239 



nutrition of the bacillus, and (2) by setting up a localized 

 reaction in the neighbourhood of the bacilli, by means of 

 which the cells are so stimulated that they are able, as we 

 have already seen, to prevent the extension of the bacilli into 

 the surrounding parts. 



Koch's fluid may not accomplish all that is expected from it ; 

 it may, in fact, be found that Koch has not completed his ex- 

 periments, but he has made a wonderful advance in our know- 

 ledge of the conditions necessary for the combating of micro- 

 organisms ; and has extended the observation of the earlier 

 workers at the globulines and albumoses who really opened up 

 the way for the advance of the numerous workers who have re- 

 cently come into the field. It would, however, take us beyond 

 the scope of the present work to say more about this marvellous 

 discovery of Koch's. Let it always be remembered that tubercle 

 destroys the tissues in which it grows, and that the treatment 

 by Koch's method completes the process of destruction, if 

 this is not already accomplished ; so that, under the very 

 best conditions, phthisis can only be stopped, and, although 

 a comparative cure may be obtained, highly differentiated 

 tissues once destroyed can never be restored or replaced. 



It will thus be seen that although Koch has selected a 

 special irritant material as that which it was found 

 necessary to separate in order to obtain the results that 

 he wished, and has obtained the sequence of specific (?) 

 stimulation of the cells, he has departed from the usually 

 accepted methods, in that he acts directly on the tissue cells, 

 and leaves the bacilli to die of starvation. It is not now a 

 case of the cells destroying or modifying the activity of the 

 bacilli ; it is simply, in the first instance, a cutting off, or 

 rather a rapid exhaustion, of the substances required for the 

 nutrition of the bacilli ; the bacilli remain, and although 

 they may eventually undergo retrogressive changes, it appears 

 probable that their spores remain for some time, at any rate, 

 ready to break out should favourable conditions again pre- 

 sent themselves. Apart from this local action, however, the 

 fact cannot be ignored that where the tissues are not already 

 too far weakened, or the cells so imperfectly nourished that 

 they cannot react to stimulus, the liquid injected by Koch 

 may exert a general and specific action on the tissue cells 

 through which they are acclimatized, as it were, to resist the 

 poison ; so that it is quite possible that a partial immunity 



