THE LUNG PLAGUE. 69 



2. The alterations in the connective tissue of the pleura, pericardium, and interlobular 

 septa have next to be described. The connective tissue of the inflamed pleura or pericar 

 dium was more or less thickened in accordance with the stage of the disease. In fresh 

 sections it was whitish or yellowish white, sometimes lardaceous, sometimes opaque and 

 yellow. Where lymph masses were adherent the epithelium could no longer be made out, 

 even when the superimposed lymph was so loosely attached as to permit it to be readily 

 stripped off. Every transition existed between this condition and that in which the 

 diseased membrane and the adjacent lymph mass appeared to pass into each other by 

 insensible gradations. In the microscopical examination of sections the most notable 

 alteration observed was the great increase in the number of cellular elements. The 

 character and distribution of these could generally be inferred from the distribution of the 

 oval carmine-stained nuclei, smooth to srooth of an inch in length, but in many parts of the 

 sections the elongated or even spindle-formed cells in which the nuclei were contained could 

 be plainly distinguished. They were imbedded in a delicately fibrillated matrix, and were 

 very generally grouped together in rows. Such rows of elements, it is well known, have, 

 until recently, been interpreted as the progeny of the connective tissue corpuscles, from 

 which they were supposed to be derived by the process of cell multiplication. The recent 

 investigations of Cohnheim, which have found very general acceptance in Germany, would 

 appear, however, to throw doubts on this view. I shall return to the subject in the sequel. 



The conditions to be observed in the thickened connective tissue septa between the 

 lobules were essentially similar to the above. The fourth photograph appended is intended 

 to illustrate these changes in the inflamed connective tissue. It is taken from No. 2817, 

 Microscopical Section, which is a portion of inflamed pericardium, and is magnified 400 

 diameters. The arrangement of the numerous nuclei, and the fibrillated character of the 

 matrix in which they are imbedded, are well displayed. 



3. The lymph masses adherent to the pleura and pericardium, and the flakes of lymph 

 which floated in the serum contained in the thoracic cavities, were composed of coagulated 

 fibrin with a variable number of pus corpuscles imbedded. The fibrin was sometimes 

 merely granular, but very often distinctly filamentous. The serum itself usually con 

 tained floating pus corpuscles ; their number being proportioned to the degree of turbidity 

 observed in the fluid. The fifth photograph appended, taken from a portion of No. 2817, 

 Microscopical Section, represents a portion of the lymph mass adherent to the pericardium, 

 magnified 400 diameters. It will be seen that the pus corpuscles are quite abundant. 



4. The transformed adipose tissue about the pericardium remains now to be briefly 

 described. Sections showed that the fat vesicles retained their shape, and generally their 

 fatty contents, but the delicate transparent connective tissue by which they are held 

 together in the normal condition was greatly thickened, and in its more or less distinctly 

 fibrillated substance numbers of new elements could be observed, as in the case of the 

 connective tissue of the diseased pleura. In the balsam-mounted sections, these appear 

 ances are well preserved with the exception that the contents of the fat vesicles have been 

 dissolved by the reagents used. The last of the appended photographs represents a portion 

 of one of these sections magnified 400 diameters. It is taken from No. 2794, Microscop 

 ical Section. 



Although the foregoing observations were very carefully made, they are far from being 

 as complete as I could have wished, and many important points connected with the his- 



