138 Dr. E. Klein on the Anatomy of [Jan. 29, 



If one examines the lungs of a guineapig which is so far advanced in 

 the process of artificial tuberculosis that the bronchial glands contain 

 cheesy deposits, one can distinguish with the naked eye two kinds of 

 morbid structure on the surface of the lungs : 



(a) Translucent structures of a circular or irregular shape, sometimes 

 projecting slightly above the surface, generally isolated, but in some 

 instances confluent, so as to form patches. The smallest are of the size 

 of the head of a small pin ; some of them are three, four, or several times 

 as large. In some lungs only the large structures are to be found ; the 

 larger kind have generally a yellowish centre. 



(6) Opaque patches of considerable diameter projecting above the sur- 

 face of the lung, some of them relatively very large (about to yL of an 

 inch), quite white, and very firm. On sections through the lung one finds* 

 that the first kind of structures correspond with cords provided with lateral 

 nodular swellings, which accompany the branches of the pulmonary artery 

 and vein. The second kind of structures correspond with nodules and 

 patches which are irregularly distributed in the tissue of the lung. On 

 microscopical examination it is seen that the first kind of structures are 

 perivascular cords of adenoid tissue, representing the follicular tissue 

 which is found in the walls of the peribronchial lymphatics in the 

 normal condition. Many of these perivascular cords or nodules are 

 supplied with a system of capillary blood-vessels. The second kind of 

 nodules, or patches, are seen to consist, on microscopical examination, of 

 a framework of trabeculge which corresponds to the interalveolar tissue ; 

 they represent trabeculse of adenoid tissue which are in continuity with 

 the perivascular cords first mentioned. The meshes of this network are 

 more or less filled out by cells lying in the spaces that were previously the 

 cavities of the alveoli. The question arises, How do these two kinds of 

 morbid structures develop, and what is their ultimate fate ? 



If one studies sections of lungs that possess very few of the first 

 kind of cords and nodules, one comes across a number of the lymphatic 

 vessels that accompany the branches of the pulmonary artery, con- 

 taining more or less numerous lymph- corpuscles. In addition to those 

 just mentioned, one is able to find lymphatic vessels, the endofchelium 

 of which is in continuity with a thin short cord of adenoid tissue that 

 stretches along the outer wall of the lymphatic, -or (as may be seen in some 

 places) projects into its cavity, thus connecting the two endothelial walls 

 of the lymphatic ; in other words, we have here a peri- as well as an 

 endolymphangial growth of adenoid tissue, connected with the endo- 

 thelium of the lymphatic. From what I have shown in the case of the 

 serous membranes, there can be little doubt that the above-mentioned 

 tuberculous cords of adenoid tissue accompanying the blood-vessels are in 

 reality only peri- or endolymphangial outgrowths of the endothelium of 

 the lymphatics. It is important to state that, at the same time, the fol- 

 licles of the bronchial adventitia increase in size, and also that a perilym- 



