1874.] the Lymphatic System of the Lungs. 141 



has a very long duration, and consequently the growth of the secondary 

 patches remains active for a long time. The network of nucleated 

 cells is, at no period of its development, such a delicate reticulum as in 

 the adenoid tissue, nor does it contain lymphoid corpuscles so regularly 

 as this latter. Moreover the adenoid tissue of the perivascular cords 

 or their lateral nodules never becomes the seat of a Jlbrous or cheesy 

 metamorphosis. The more the lung has advanced in the process of 

 artificial tuberculosis, the more do we find the tissue of the lung, 

 in the neighbourhood of the primary and secondary nodules, undergoing 

 inflammatory changes consisting in thickening of the alveolar septa, 

 and in a granular condition of the walls of their capillary blood-vessels, 

 the nuclei of which are in active proliferation, their number being out 

 of proportion large. 



In the peripheral parts of the lung the most numerous secondary no- 

 dules are to be met with ; and consequently the most numerous cheesy 

 deposits are here to be found. I have often seen a system of large patches 

 projecting somewhat above the surface and radiating towards the deeper 

 parts, as the terminal branches of a minute bronchus pass towards the 

 stem. 



The secondary process extends from the terminal branches (alveoli and 

 infundibula) to the large bronchi. In these the process becomes very 

 marked, and consists of the following changes : 



(a) The epithelium proliferates very abundantly, whereby the cavity 

 may finally become almost completely plugged up by the progeny of the 

 epithelium. 



(6) A more important change consists in the proliferation of the tissue 

 that we have designated above as pseudostomata, namely the branched cells 

 of the tunica mucosa that extend between the epithelial cells to the surface ; 

 this tissue grows so as to form a very rich adenoid tissue. At the same 

 time there goes on an active growth of adenoid tissue in the walls of the 

 peribronchial lymphatics ; that is to say, there is a hyperplasia (Sander- 

 son) of the preexisting follicles, as well as a new formation. [The most 

 active transformation of the pseudostomatous tissue of the bronchi into 

 adenoid tissue I have met with was in rabbits suffering from chronic 

 pyaemia ; it has been already stated that the reticulum of branched cells 

 which stretches between the epithelial cells of the surface is better 

 developed in rabbits than in guineapigs, in the normal condition.] 



(c) In the large bronchi, which have become involved in the secondary 

 process, another noteworthy change takes place, viz. the fusion of groups 

 of the proliferating epithelial cells, not only those of the free surface, 

 but also those of the mucous glands, so as to form multinuclear proto- 

 plasmic cylinders and lumps (giant cells). 



The secondary process, viz. that which affects the alveoli and bronchi, 

 and which may be justly called the catarrhal pneumonic process, 

 always accompanies artificial tuberculosis when it has extended to the 



