70 DEPAETMENT OF AGEICULTUEE. 



tology of the diseased parts, remain untouched. Still I entertain the hope that what I 

 have been enabled to accomplish with the opportunities at my disposal, will possess some 

 real value, particularly as the course pursued of preserving sections in a permanent form 

 will permit these to serve for further study in the future, in connection with any similar 

 investigations that may hereafter be undertaken in this country. 



It will be observed, from the descriptions I have offered, that the disease is one of 

 those intense and rapidly spreading inflammatory affections characterized by the develop 

 ment of what Rokitansky formerly described as croupous exudates, on the surface of the 

 affected serous membrane, and in the parenchyma of the organs involved. The examina 

 tion of specimens taken from animals dead at different periods during the course of the 

 disease, and the study of different portions of the same lung when a part is comparatively 

 healthy and a part diseased, would seem to indicate the correctness of the opinion of 

 Professor Weber* that the pleura is primarily involved, and that the parenchyma of 

 the lung is only affected secondarily, after the pleura coating the lobules, and the con 

 nective tissue trabecula} connected with it, have become involved. The comparatively 

 healthy condition of the air passages, or at least of those portions of them which are not 

 imbedded in the hepatized parts of the lung, is particularly worthy of note. 



In its histological relations, it will be perceived that the disorder is characterized by 

 the appearance of immense numbers of pathological elementary forms in the parts involved. 

 These appear in the air vesicles of the lungs, in the lymph masses adherent to the pleura 

 and the pericardium, and in the abundant serous fluid which accumulates in the thoracic 

 cavities, under the well-known form of pus cells. In the sections of the inflamed con 

 nective tissue of the pleura and pericardium, the connective tissue of the interlobular 

 trabeculas, and of the adipose tissue about the pericardium, the new elements do not, 

 however, sufficiently resemble pus cells to permit me to assume them to be such without 

 hesitation. 



In describing the sections of the inflamed pericardium and pleura, I have already 

 mentioned that the nuclei were oval in form, g-aVoth to lo orrth of an inch in long diameter, and 

 generally grouped together in rows of two, three, or more elements ; and I mentioned that 

 the views of Virchow, by which these rows were interpreted as the progeny of the pro 

 liferation of the normal connective tissue corpuscles of the part, were assailed by the 

 recent investigations of Cohnheim. According to this observer they are, in fact, rows of 

 white blood corpuscles, which have made their way through the walls of the blood ves 

 sels during the inflammatory process, and which are found in longer or shorter rows sim 

 ply because in their &quot;wandering&quot; they are obliged to follow the course of the natural 

 channels which exist in the tissues. Now, the pus corpuscles above described in the 

 lymph masses, and in the cavities of the air vesicles, can readily be understood to have, 

 perhaps, had this origin; certainly none of the lung sections I have preserved exhibit any 

 appearances which would indicate that their pus corpuscles were genetically connected 

 with any process of proliferation going on in the normal anatomical elements of the lung. 

 But with the new elements observed in the inflamed connective tissue, this explanation is 

 not so satisfactory. Take, for example, the sections of the inflamed pericardium. Here 

 the nuclei of the numerous new cells, seen in the sections, resemble the nuclei of em 

 bryonic connective tissue corpuscles, and not those of pus. And where it is possible, as 



* Loc. cit. 



