198 THE DISEASES OF DOMESTIC A^HMALS. 



Gelatinous, infiltrated portions of the lungs are more or less 

 transparent, densely filled witli fluid, and extended to a moderate 

 degree. The fluid in sucli parts is viscid. The changes in these 

 parts become -more marked as the fluid in the alveoli augments. 

 When Tve make a transverse section of such parts, this fluid does 

 not flow over the cut surface, which is smooth and lustrous, unless 

 we exert pressure upon the lung. The contents of the alveoli 

 strongly resemble mucus, but, as there is no mucous membrane in 

 the alveoli, it terminates with the brouchiolus ; if this fluid contains 

 mucin, it must then be aspirated with the air. It does not, how- 

 ever, contain mucin. This fluid is very viscid and much like the 

 white of eggs ; it also contains cells, most of which strongly resem- 

 ble the white blood-cells ; some of them are larger, and are undoubt- 

 edly desquamated and swollen endothelial cells. 



Accordingly, the disease product in the lungs consists of a viscid 

 fluid and cellular elements ; this mass seems to be of a movable 

 nature, and it is quite interesting to know why it is not expecto- 

 rated. 



At first, however, I will remark that I can not accept the termi- 

 nology, " inveterate oedema," which Rindfleisch has given to this 

 condition, especially as he attributes it to the extravasation of the 

 serous elements of the blood in consequence of mechanical hinder- 

 ance to the circulation. On the contrary, we have here to do with 

 an inflammatory process, as is indicated by the presence of so many 

 round cells in the fluid. Laennec was the first to give the name of 

 " gelatinous infiltrations " to these conditions, and Briickmiiller has 

 also treated it as an inflammatory process. In it the extravasation 

 of fluid far exceeds that of the cellular elements of the blood, 

 which, with the desquamated epithelium of the alveoli, make up 

 the mass. "When this occurs alone we have a desquamative pneu- 

 monia, which is similar to the desquamation which occurs from 

 the cutis, except that the loosened cells are here inclosed in a cav 

 ity ; the presence of the fluid in this case causes them to swell, 

 and become more or less transparent, the same as when we put tlie 

 desquamated cells of the cutis-e'pithelium in water. As in most 

 pneumonias, there is also an exudation of fluid from the vessels into 

 the alveoli ; the name of catarrhal pneumonia is better than Buhl's 

 terminology, " desquamative j^neumonia." Horses have, in general, 

 this form of pneumonia, although not every catarrhal pneumonia 

 is complicated with gelatinous infiltration. 



The conditions to the development of gelatinous infiltration are : 



1. ^^Atelectasis of tJie comjplicated jpuhnonary tissue — i. e., the 



