THE HORSE. 199 



complicated portion of the lungs must first be airless before the 

 inflammatory processes take place. The atelectatic parts have a 

 more or less homogeneous character, and, when they become filled 

 with this fluid substance, they have the above-mentioned gelatinous, 

 pellucid character. The atelectatic parts are rendered cedematous by 

 the inflammation ; fluid and cells distend the alveoli instead of air; 

 such parts are tense, yet elastic to the touch. "We have, then, atelec- 

 tasis — airlessness — plus inflammatory oedema." 



" It may be remarked that we have two forms of oedema : the 

 one mechanical, due to some interference with the circulation, by 

 which the vessels become so distended that the serous elements of 

 blood exude through the vessels ; this is exemplified by the collat- 

 eral cedeiaa, which often takes place in the non-complicated parts of 

 the lungs in pneumonia, that causes death by a sort of internal 

 self-drowning. The other is due to inflammation, which you should 

 know all about." 



2. " A second condition proper to gelatinous infiltration is anae- 

 mia ; or, in other words, bloodless atelectasis is a sine qua non to ge- 

 latinous infiltration. This anaemia is the reason that such parts 

 have a yellowish or yellowish-gray color. According to Rindfleisch, 

 a hypersemic condition develops in every atelectatic part. This 

 hyperemia is the cause of the exudation of the blood-serum in the 

 alveoli, and causes a condition which he names splenization. His 

 ' inveterate oedema ' is only to be distinguished from splenization 

 by the absence of hyperemia, and the anaemia by the pressure 

 caused by the continued transudation of fluid into the alveoli." 



According to Schutz, neither splenization nor gelatinous infiltra- 

 tion are due to mere serous transudation. Both owe their genesis 

 in atelectatic tissues to inflammation, except in splenization the ate- 

 lectasic tissues are in a hypersemic, while in gelatinous infiltration 

 they are in an anaemic condition. The splenized and gelatinous 

 infiltrated tissues contain not only serous fluid, but the products 

 of inflammation, i. e., water, which is rich in albumen and cellular 

 elements. Gelatinous infiltration is, therefore, not the second stage 

 of splenization, as Rindfleisch asserts, but either can occur sui gene- 

 ris, and we have therefore to consider why at one time we have 

 gelatinous infiltration and at another splenization of the lung. 



" I have only seen gelatinous infiltration in emaciated and weak 

 horses, which were anaemic. It makes no difference whether this 

 latter condition was produced by poor dietetic conditions or chronic 

 disease. In such horses all parts are pale, also the atelectatic por- 

 tions of the lungs ; and slight catarrhal processes in such parts easily 



