The Bacillus tuberculosis. 



141 



account of, or caused by, the bacilli; it is seen originating and deve- 

 loping without the bacilli. These organisms invade the tissue in question 

 subsequent to its formation, and solely because it is a culture-medium 

 favouring their predominant development. 



To consider, as Koch does, giant-cells as mere special capsules of 

 the bacilli is a mistake not warranted by anything. 



As soon as tubercle-tissue undergoes complete cheesy degeneration 

 and softening, the bacilli — Koch acknowledges this also — disappear 

 from that locality nearly altogether, because no food is left and be- 

 cause the fat resulting in that process acts deleteriously upon them. 

 This is also against the etiological relation of the bacilli with tuber- 

 culosis. In examining the sputa of a number of undoubted cases of 

 pulmonary phthisis from the Philadelphia Hospital, I was unable to 

 detect the bacillus in a certain number, and these were usually cases 

 where cheesy degeneration had made great progress, as indicated by 

 great loss of substance. This also would seem to show that advanced 

 cheesy degeneration does not favour the development of the bacillus, 

 and that the latter cannot serve as a point in diagnosis by the sputa. 



Koch further claims that the Bacillus tuberculosis differs from 

 other bacilli morphologically, and in its behaviour to staining fluids. 

 We cannot confirm this. My assistant, Mr. Bodamer, and myself, after 

 prolonged study with instruments as good as those of Koch, and after 

 using all known methods of staining, have failed so far to see any 

 special features in the bacillus in question which would make it distinct 

 from other bacilli. 



If Koch's bacillus even were possessed of distinct morphological 

 features, it would not materially help to make it a specific organism. 



Prof Wood and myself made the observation that bacteria may 

 acquire special morphological and physiological features in culture; 

 excluding fully the possibility of Koch's „Verunreinigungen". More- 

 over, we have seen micrococci increase in size under certain conditions 

 of culture. This is more interesting, as Prof Rothrock, of the Uni- 

 versity, made the suggestive observation that lower fungi or algae, 

 under culture, perhaps from pathological conditions of their own, may 

 undergo decided, perhaps permanent modification in their anatomy. 



It appears to me, however, that the bacillus may still play a very 



