i;o MICRO-ORGANISMS AND DISEASE. [CHAP. 



like bits of gutta-percha inserted into the peritoneal cavity, 

 &c.), were really due to accidental contamination with 

 tuberculous material. 



According to my own experience extending over a very 

 large number of cases of human miliary tuberculosis and 

 tuberculosis of cattle, I cannot for a moment accept the 

 statement that the bacilli found in the two affections are 

 identical ; for I find that in the two diseases their morpho- 

 logical characters and distribution are very different. The 

 bacilli of human tuberculosis are conspicuously larger than 

 those of the tuberculosis of cattle, and in many instances 

 more regularly granular. As is seen in Figs. 88-90, those 

 of human sputum are nearly half, or at least one-third, 

 as large again as those of the caseous masses from the lungs 

 of cattle. 



The bacilli in the tuberculous deposits of cattle are always 

 contained in the cells ; the larger the cell the more numerous 

 the bacilli. This fact comes out very strikingly in thin and 

 well-stained sections. Around many of the smaller and larger 

 clumps of bacilli the cell-outline is still recognisable, and when 

 the cell disintegrates, as it does sooner or later, the bacilli 

 become free in groups ; in this respect there exists a 

 remarkable similarity between leprosy and bovine tuber- 

 culosis. But in the human tubercles the bacilli are always 

 scattered between the cells. 



I cannot agree with Koch, Watson Cheyne, and others, 

 who maintain that each tubercle owes its origin to the 

 immigration of the bacilli, for there is no difficulty in 

 ascertaining that in human tuberculosis, in tuberculosis 

 of cattle, and in artificially-induced tuberculosis of guinea- 

 pigs and rabbits, there are met with tubercles in various 

 stages young and adult in which no trace of a bacillus 

 is to be found ; whereas in the same section caseous 



