TUBERCULOSIS OF THE LUNGS. 211 



tubercular matter, nor upon diffuse development of tubeicle, but upon 

 morbid processes of a different nature. 



In the lungs it is more especially the residua of chronic inflamma- 

 tion which Laennec and his pupils have regarded as tubercular infiltra- 

 tion. The main source of their error was the idea that caseous meta- 

 morphosis^ to which tubercle of long standing almost invariably is 

 subjected, was a specific peculiarity of the disease, and that it might 

 be regarded as a diagnostic mark, by which the tuberculous nature of 

 a growth, wherein the process arose, might be determined. Accord- 

 ing to such views, the product of chronic pneumonia, which often ap- 

 pears in phthisical lungs independent of tubercle, was ascribable to 

 tuberculosis, since, generally speaking, this inflammatory product at 

 first is moist, transparent, and of a grayish or grayish-red color, and, 

 after a lapse of time, becomes transformed into dry, opaque, yellow, 

 cheesy masses, and, subsequently, into a creamy or curdy, flocculent 

 liquid ("tubercular" pus). 



But the point of view, from which caseous metamorphosis was con- 

 sidered a characteristic sign of tuberculosis, is obsolete. It is well 

 established that not only tubercle but many other formations with 

 which it has nothing in common, such as old, cancerous nodules, lym- 

 phatic glands enlarged by hyperplastic cell-growth, haemorrhagic in- 

 farctions, incapsulated collections of pus, may all undergo caseous 

 metamorphosis, and the term tuberculization, which has been produc- 

 tive of great confusion, and against which I have long protested, has 

 fallen into disuse. 



By this important step in pathological anatomy, for which we are 

 chiefly indebted to Virchow, the very foundation of the teachings of 

 Laennec is swept away. His fundamental idea that all pulmonary 

 consumption depends upon neoplasm, after having exercised a most 

 baneful influence both upon the prophylaxis and the treatment of the 

 disease, is no longer tenable, and it is really incomprehensible that the 

 majority of physicians of the present day should still adhere to his 

 views. 



Although the consolidation and destruction of the pulmonary tis- 

 sue in consumption is mainly a result of inflammation, yet the frequent 

 coexistence in phthisical lungs of the products of chronic pneumonia 

 and tubercle renders it improbable that the presence of the latter 

 should be purely accidental, and suggests a causative connection be- 

 tween tubercle and the inflammatory lesions. According to the com- 

 mon opinion, this connection is, that tuberculosis is the primary affec- 

 tion, to which the pneumonic process is secondary and dependent. It 

 cannot be denied that this view is right in certain cases ; in a great 

 majority of instances, however, the converse is true ; the tuberculosis 



