INFECTIOUS PNEUMONIA. 
333 
Pathology and Morbid Anatomy .—The process is character¬ 
ized by inflammatory hypersemia of the lung - tissue, and also by 
the exudation of coagulable material into the pulmonary tissue. 
This process consists of three stages : engorgement, red and 
grey hepatization. In the state of engorgement we have the 
following changes take place : The organ is of a dark red color, 
• its specific gravity and weight are increased, its elasticity is 
diminished, and it does not crepitate on pressure ; if cut into, its 
surface yields a reddish, frothy, tenacious liquid. In the second 
stage we have migrations of blood corpuscles into the pulmonary 
tissue, the lung is much heavier than in the preceding stage, it 
is also increased in size, the pleura over the inflamed lobe is 
covered with lymph and sometimes it is bulged out. The lung 
is quite solid, sinks in water, and cannot be inflated, does not 
crepitate under the fingers, and is friable, breaks down with a 
soft, granular fracture. Third stage.—Toward the base of the 
inferior regions of the lungs may be found zones of hepatization, 
on section they show a darkish red color, with a few greyish 
islands ; these islands vary in size, some being as large as an 
orange, and others not larger than a small marble. When of 
recent origin, they are surrounded by a white zone formed by 
leucocytes. On their surface, cavities are found ranging in size, 
these cavities contain necrosed pulmonary tissue. Finally we 
find purulent centres containing a whitish pus mixed with 
gangrenous pulmonary tissue. As a general thing, the appear¬ 
ance of the lungs in cases of death in infectious pneumonia are 
uniform, viz., almost complied disorganization of each lung 
with numerous and separate abscesses and often with gangrene 
of parts of the lung affected. The blood in the left cavities of 
the heart is generally dark and thin. Symptoms : First there 
is rigors, with a staring coat, disturbance of animal heat, with 
coldness of skin and extremities, all connected with perturbed 
nutrition. There is also languor, capricious appetite, visible 
mucous membranes are of a dull, rusty color, pulsation of the 
submaxillary artery is increased in frequency, with the vessel 
feeling somewhat full. The temperature generally runs as high 
as 105 or 106 Fahr. 
