440 TUBERCULOSIS. 



nature of tubercle really is can be given only after an accurate 

 examination of facts. 



Tuberculosis of the Lungs. In order to properly group the dif- 

 ferent phenomena of tuberculosis of the lungs, it will be of 

 advantage to first illustrate its four principal varieties. 



" Chronic tuberculosis n comprises a tolerably well-defined 

 group, which may be called " localized tuberculosis/ 7 as " chronic" 

 is an expression mostly clinical. This form appears most fre- 

 quently in the apices of the lungs, simultaneously in both, 

 although this is not without exceptions. As it is never fatal, per 

 se, we are rarely able to study it as a disease by itself. We meet 

 with it, as an intercurrent condition, in the bodies of individuals 

 dead of other diseases. 



We find, imbedded in the lung-tissue, nodules of about the 

 size of a millet- or hemp-seed, which have a gray or grayish-yel- 

 low color, are homogeneous, and of soft, or moderately firm, con- 

 sistency ; or we see nodes, the size of a lentil or an almond, 

 distinctly marked from the surrounding tissue. These are cir- 

 cumscribed infiltrations, which, in transverse section, appear al- 

 most dry, homogeneous, and of a yellowish-red or yellowish-gray 

 color, which are in firm connection with the adjacent structures, 

 and not yielding juice or tissue-particles on being scraped with 

 the knife. Or, lastly, we find nodules or infiltrations of the size 

 before described, whose centers are usually soft and friable, which 

 can be mashed with the fingers, and from which the scraping- 

 knife can reduce crumbs and brittle particles. In the apices, in 

 some cases, nodules are the only formations present, and these 

 may be found either isolated or conglomerated into groups ; in 

 other cases we encounter only nodes, and therefore infiltrations. 

 Not infrequently we see in the same apex a varying number of 

 both nodules and nodes. 



All subsequent changes of these formations relate chiefly 

 to the healing process; for, provided that no recurrences take 

 place, localized tuberculosis of the lungs, as a rule, terminates in 

 a cure. 



The healing process may be accomplished in two ways. Either 

 it may start in the nodule or the infiltration while they are still 

 in connection with the lung structure, and they themselves rep- 

 resent a tissue, though a morbid one. Or the healing process 

 may start after the nodule or the infiltration have been trans- 

 formed into a brittle, friable mass, and therefore have ceased to 

 be a tissue. 



