Pathogenesis. 177 



catarrhal symptoms. The disease which develops in this 

 manner may, after the disappearance of the infective agent 

 from the body, terminate in recovery within a short time. Most 

 cases of the catarrhal form of influenza follow this course, 

 while an unusually severe infection may result in a very severe 

 septic manifestation, and cause the death of the animal within 

 a few days. The autopsy findings in such cases are similar 

 to those of hemorrhagic septicemia, with hemorrhages in the 

 serous and mucous membranes, hyperemia, and small hemor- 

 rhages in the parenchymatous organs, especially in the lungs 

 and kidneys, but as in such cases the bacteriological examina- 

 tion not infrequently shows the presence of the bipolar bacilli 

 in the organs as well as in the blood, there exists a possibility 

 that they have taken part in the fatal termination of the disease. 

 These organisms enter the blood in an early stage of the dis- 

 ease, multiply in the same very rapidly, and are frequently 

 the direct cause of death, or at least they hasten death. 



The primary infection, that is, the general febrile condi- 

 tion, may weaken the body to such an extent that the facultative 

 pathogenic bacteria, especially the ovoid bacteria and strepto- 

 cocci, can exert their specific infective action. As a result of 

 their invasion inflammatory processes develop, especially in 

 the lungs, in the form of pneumonia or pleuro-pneumonia, while 

 the primary infective agent has possibly in the meantime dis- 

 appeared from the body. 



The bipolar bacillus, as well as streptococci, may produce 

 such inflammation ; usually, however, in the cases where pleuro- 

 pneumonia caused the early death of the animal, under mani- 

 festations of a violent septicemic character, the pleural exudate 

 and the affected lung tissue contain the ovoid bacteria ex- 

 clusively, while the streptococci appear to multiply more rapidly 

 only later in exudates which have already developed as the re- 

 sult of the disease. These latter are present in predominating 

 numbers or sometimes even exclusively in the hepatized and 

 necrosed lung tissue, while in the pleural exudate they are 

 usually found exclusively (the pleurisy apparently being caused 

 only by the streptococci which pass from the lungs into the 

 pleura). Streptococci may also' enter the blood, and in this 

 way they may reach the parenchymatous organs when they may 

 be found on autopsy in the spleen, the kidneys, and in the 

 lymph glands. 



Other bacteria may in some cases cause a secondary infection; 

 thus, in one of our cases, besides the bipolar bacillus, the diplococcus 

 lanceolatus (recently also demonstrated by Meyer), in another case 

 the bacillus pyocyaneus, were present in great numbers. Besides these 

 the colon bacillus may often be found in the inflamed lung tissue. 

 The eventual necrosis of the inflamed lung tissue may be due to the 

 bipolar bacillus or to the streptococcus. In several cases the gan- 

 grenous lesions have contained the bacillus necrophorus, which indi- 

 cates that in this process, at least under suitable conditions, this 



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