Symptoms. 179 



In the hepatized tissue numerous necrotic areas may fre- 

 quently be disseminated, which vary in size from that of a 

 poppy seed to a hazelnut. They are of a dirty, grayish-brown 

 or greenish color, and of a mushy consistency. In some cases 

 a circumscribed portion of the affected lung is changed into 

 a necrotic mass which may attain the size of a fist or a child's 

 head, and may sometimes be surrounded by a layer of pus. 



The mucous membrane of the bronchi and trachea is bright 

 red, swollen, not infrequently sprinkled with hemorrhages, and 

 profusely covered with sero-purulent secretion. 



Inflammation of the superficial layers of the lung is always 

 associated with pleurisy. The pleura loses its luster as a 

 result of a desquamation of the epithelial layer, is dull, rough, 

 and covered by loose, moist, smeary pseudo-membrane. This 

 peels off readily, and is of icteric yellow color, and somewhat 

 resembles pudding. Between the two layers of the pleura there 

 is a yellov/ish fluid which contains flakes of the fibrinous mem- 

 brane. This exudate is cloudy, and is sometimes present in 

 considerable quantities, exerting more or less pressure on that 

 portion of the lung which is not hepatized. In less acute cases 

 there is a thick, wide connective tissue layer under the loose 

 false membrane. If the pleurisy develops in connection with 

 superficial necrotic fields, or as a result of the rupture of such 

 an area, the exudate is always of a purulent or ichorous char- 

 acter. In case the gangrenous area which opened into the 

 pleural cavity communicates with the bronchi, pneumothorax 

 or pyo-pneumothorax will develop. 



In other respects the autopsy reveals conditions similar 

 to those present in the catarrhal form of influenza, only the 

 changes are usually somewhat more pronounced. On the 

 mucous membranes not infrequently superficial ulcerations may 

 be found besides the catarrhal reddening and swelling. The 

 parenchymatous degeneration of the heart muscles, the liver 

 and in the kidneys, frequently passes into a fatty degeneration. 

 Small hemorrhages or even extensive suffusions are often 

 present in the tissue of the serous membranes as well as in 

 the endocardium. The lymph glands, especially those of the 

 thoracic cavity are greatly swollen. Suppurative areas may 

 exceptionally be found in various organs, and purulent inflam- 

 mation of the joints. 



Symptoms. The time of incubation in influenza extends 

 in the majority of cases from 3 to 7 days ; less frequently, es- 

 pecially after the animal has contracted a cold, the first symp- 

 toms may appear after 24 to 48 hours, while in other cases the 

 disease may remain latent for 8 to 9 days. In some eases 

 the animals are affected for a time only with a slight bronchial 

 and stomach catarrh, while the manifestations of the pectoral 

 form of influenza gradually develop later. In these cases the 

 time of incubation "appears to be considerably longer, although 



