l()-4- IiiUauimatiuii of the I'lc'iira. 



fibrin membranes which cover tlie affected portion of lungs 

 Avith iibrino-purnlent (k'posits. Occasionally tliere may be an ex- 

 travasation of numerous red blood corpuscles, or the exudate 

 assmiies a more or less hemorrhagic tinge (pi. hemorrhagica), 

 while the entrance of saprophytic bacteria causes putrefaction 

 and an ichorous condition of the exudate (pi. ichorosa). 



Under the microspope the serous exudate shows few emlothelial cells, generally 

 in a condition of fatty degeneration, and niinierous leucocytes ; the fibrinous coagula 

 contain leucocytes in a reticular matrix. The purulent exudate consists preferably 

 of intact or fatty degenerated leucocytes; while the ichorous exudate contains much 

 granular detritus, fat droplets and shreds of tissue. The chemical analysis of 

 the exudate shows allniriinoid substances in larger amounts; 3 to G'/f in the sero- 

 fibrinous exudate, and according to Boiteux even 6 to 8.5%, 



When there is a considerable mass of fluid in the pleuritic 

 cavity, the lungs, which are already collapsed, are further com- 

 pressed in proportion to the amount of fluid present; they 

 therefore become gradually smaller and poorer in air. Those 

 portions of lung which are in the neighborhood of the exudate 

 become completely void of air, flaccid and of fleshy consistency ; 

 the cut surface appears uniformly dark red (compression ate- 

 lectasis, splenization). When the exudate is abundant, the 

 mediastinal lobe in horses may undergo a twist outward and 

 backward, which displacement, according to Dieckerhoff, al- 

 ways leads to death, because it prevents the absorption of the 

 exudate. (Mathis found in a dog a complete torsion of the 

 right posterior lobe.) 



Chronic pleuritis begins with the formation of vascular 

 granulation tissue (pleuritis granulosa), which gradually be- 

 comes fibrous and cicatricial (pi. fibrosa s. productiva) or ad- 

 hesions form between the pleura costalis and pulmonalis (pi. 

 adhaesiva). 



Papillomatous granulations occasionally grow out of the tissue of the pleura; 

 Hutyra reported a case where they were very high, branching, and so numerous 

 that they formed a mass the si?e of a child 's heart. Cadiot and others have seen 

 the formation of similar granulations on a tuberculous base. Kowalewsky described 

 a case of pleuritis ossificans in a cow. 



A fluid exudate is likewise not rare and is either purulent, 

 and in this case surrounded by a connective tissue capsule 

 (preferably in the presence of bacillus pyogenes or of foreign 

 bodies), or serous or hemorrhagic. In horses, peculiar cases 

 of serous, chronic pleuritis are observed where the serous mem- 

 branes contain a large amount of serous or slightly purulent 

 fluid and where the pleura is studded with thick, fibrinous de- 

 posits containing numerous small abscesses. (Streptococci 

 pleuritis, Bang.) 



Symptoms. The initial stage of pleuritis leads to variable 

 s^Tiiptoms, according to whether the disease is primary or 

 secondaiy. 



