20 ARTIFICIAL PRODUCTION OF TUBERCLE. 



tissue can be seen, and the cells lining them appear to be the sole representatives 

 of cell-forms (with the exception of the nuclei of the capillaries and of some 

 fusiform nuclei), in the delicate membrane of which the wall of the alveoli is 

 composed. Under certain morbid processes, especially of the catarrhal type, 

 they enlarge and desquamate; and we then call them epithelial cells which 

 have separated. At other times, however, the structure no longer produces 

 epithelial cells, but cells which are the direct derivatives of connective tissue. 

 A few large cells like epithelium are occasionally produced ; but these latter 

 do not, as a rule, form a large proportion of the grey granulation in the lung. 

 The epithelium passes away, or, at any rate, does not maintain its type in the 

 process of the new growth. There is no filling of the alveoli — at least, not to 

 any proportionate extent — with epithelial forms ; and thus far we have not 

 been dealing with anything like ordinary pneumonia, and the process is 

 absolutely dissimilar from that of pyaemia. 



It appears also that, in the lung, the point of departure of the growth 

 is in no essential respect from the vascular apparatus ; nor is this implicated 

 in the same manner as it is in most inflammatory processes. The point of 

 departure, even when it is connected with the vessels, is in a tissue external 

 to the vessel; and the occlusion of the circulation which occurs round the 

 growth is either through pressure, or by the implication of the walls of the 

 capillaries in the growth ; and it passes backwards from them to the smaller 

 arteries, and not in the converse direction. 



I think that there can be very little question but that the affection in 

 the lymphatic glands is one so closely akin to the tubercular change, that 

 I need not dwell upon it further. 



The organ which might excite most doubt is the liver, because, in 

 man, tubercular growths here very seldom proceed to the same extent 

 as is observed in the guinea-pig. But really, in its essential characters, this 

 growth appears to me to be identical with that of tubercle in the human 

 liver. Their seat is the same; their relation to the acini is the same; and 

 in both we see the same immunity of the proper liver-structures from all 

 participation in the process of the new growth ; and I think I may say 

 that we know of no other disease except tubercle to which the description 

 I have given of the growth in the liver can apply. The only one producing 

 at all analogous effects in the liver is leucocytha^mia, and to that I will 

 allude in a few moments. 



As regards again the omentum, any one who will compare for a moment 

 one of these growths with specimens of tubercular granulations from the 

 human omentum, or from that of the monkey, can have, I think, but very 



