Pathogenesis. gi 



the skin or mucous membrane directly into tlie blood stream, 

 death results in a shorter time (Tiede found bacilli in the in- 

 ternal organs of a mouse 15 minutes after subcutaneous inocul- 

 ation). Death is caused in the first place by the action of the 

 toxins which without a doubt form in the animal body in such 

 a manner that through the negative chemotaxis of the virulent 

 bacteria the phagocytes are unable to exert their action (Gabrit- 

 schewsky, Silberbeg & Zeliony). The chemotaxis of the at- 

 tenuated bacteria is on the other hand positive, and this ex- 

 plains the local suppurative inflammation which usually ter- 

 minates in recovery after a subcutaneous injection of such a 

 virus. 



Injections of attenuated virus into the chest muscles of 

 chickens produce a serous inflammation of the connective tissue 

 and degeneration of the musculature (see page 95). 



The bacteria penetrate from the blood circulation into eggs, and 

 they have been found in the yolks of eggs of affected animals (Celli 

 & Marchiafava, Barthelemy). The first two authors have also demon- 

 strated the transmission of the disease to the progeny; on the other 

 hand, Kitt found that young rabbits (4-6 weeks old) descending from 

 artificially immunized animals resist a virulent infection. 



Anatomical changes. The principal anatomical findings in 

 acute cholera consist in an acute hemorrhagic inflammation 

 of the intestines and lungs in association with small hemor- 

 rhages on the serous membranes and sometimes a fibrinous 

 exudate on the same. The blood vessels of some of the loops 

 of the intestines are injected and their peritoneal covering 

 also contains small punctiform hemorrhages. The intestinal con- 

 tents are fluid, mixed with mucus and fine bloody streaks, or 

 of a uniform reddish color from the admixture of a considerable 

 quantity of blood. The intestinal mucous membrane appears 

 reddened sometimes only in spots and again in longer portions, 

 particularly in the duodenum. It shows an inflammatory swell- 

 ing and is studded with dark red hemorrhages; exceptionally 

 small round diphtheritic ulcers are also found on the intestinal 

 mucous membrane (frequently in water fowl). 



The serous content of the pericardium is frequently cloudy 

 and contains small fibrinous flakes ; the epicardium appears as 

 if sprinkled with blood and is frequently covered with fine 

 fibrinous membranes, particularly in water fowl. 



The lungs are congested and edematous, sometimes dark 

 brownish red in spots and hepatized as an indication of a 

 croupous hemorrhagic inflammation which is sometimes as- 

 sociated with a fibrinous pleuritis. The mucous membrane of 

 the upper air passages shows catarrhal reddening and swelling. 



In the parenchymatous organs the first stages of parenchy- 

 matous degeneration may be observed. The regional lymph 

 glands of the spleen and cecum are almost invariably decidedly 

 swollen and hemorrhagic. Exceptionally a fibrinous inflamma- 



