22 ARTIFICIAL PRODUCTION OF TUBERCLE. 



arbitrary definitions of tubercle. I think, if I may pass such a criticism 

 without presumption, that some modern pathologists are rather disposed too 

 strictly to limit the application of the term tubercle. Even Virchow's careful 

 observation, to which we owe so much — that all cheesy matter is not tuber- 

 cular — has been since pushed to an almost dangerous extreme ; so that some 

 are even disposed to doubt the tubercular character of any cheesy matter; 

 whereas, on the contrary, tubercle is among the most frequent, though not the 

 sole cause of such products in the body. Indeed, these limitations of tubercle 

 have proceeded so far that, if the exclusion of the different forms from the 

 category of tubercle proposed by various pathologists were simultaneously 

 carried out, tubercle would, not unfortunately, cease to exist, but would 

 certainly no longer have any place in our nosologies ; for nearly every patho- 

 logical product hitherto ranked under this title, from the grey granulation 

 to the yellow granulation and the cheesy infiltration, is by some authority 

 or other excluded from the category of tubercle. I would not for a moment 

 say that I think that no limitations to the class of tubercle are desirable; 

 but I think that we are at present in danger of carrying these to an extreme 

 degree. My impression is, that tubercle is a product which undergoes 

 transformation in various directions ; but that, though it varies somewhat in 

 appearance, especially in the lung, according to the rapidity of its development 

 or the greater or less amount of implication of epithelial structures in the 

 process of its growth, and though it may, at one stage of its growth or trans- 

 formation, present appearances different from those observed at another, yet 

 that these stages and varieties of appearance are not the less tubercle. 



There is, however, another point to which I desire especially to call 

 your attention, in relation to the question of the identity of the disease in 

 the gmnea-pig and in man. This question appears to me to rest on a broader 

 basis of analogy than that of the correspondence in every line and shade 

 of description between the statements of individual observers, as regards 

 either the histological characters of these growths in the rodentia or those 

 of tubercle in man. Looking at the general history of histological research, 

 I cannot for a moment flatter myself that I have exhausted all the points in 

 the minute anatomy of these new formations ; though I think that I have, so 

 to speak, been able to lay before you the leading features of their ultimate 

 structure. But what I wish to insist on is the general or constitutional character 

 of the affection, which coupled with the general analogy of the new growths 

 with tubercle, I think, almost absolutely proves their tubercular nature. It is 

 not a question of the lung alone, or of the liver alone, or of the lymphatic 

 glands, or the spleen, or the omentum or intestines considered singly. It is a 



