Pathogenesis 455 



studied more or less similar toxic products. The real toxic 

 substance is, however, not known. 



Pathogenesis. Through what activity the cholera or- 

 ganism provokes its pathogenic action is not yet deter- 

 mined. The organisms, however, abound in the intestinal 

 contents, penetrate sparingly into the tissues, but slightly 

 invade the lymphatics, and almost never enter the circula- 

 tion ; hence it is but natural to conclude that the first ac- 

 tion must be an irritative one depending upon toxin-for- 

 mation in the intestine. 



In the beginning of the disease the small and large intes- 

 tines are deeply congested, almost velvety in appearance, 

 and contain liquid fecal matter. The patient suffers from 

 diarrhea, by which the feces are hurried on and be- 

 come extremely thin from the admixture of a copious 

 watery exudate. As the feces are hurried out, more and 

 more of the aqueous exudate accumulates, until the intes- 

 tine seems to contain only watery fluid. The solitary 

 glands and Peyer's patches are found enlarged and the 

 mucosa becomes macerated and necrotic, its epithelium 

 separating in small shreds or flakes. The evacuations of 

 watery exudate rich in these shreds constitute the char- 

 acteristic "rice-water discharges" of the disease. As the 

 disease progresses, the denudation of tissue results in the 

 formation of good-sized ulcerations. Perforations and deep 

 ulcerations are 'rare. Pseudo-membranous formations not 

 infrequently occur upon the abraded and ulcerated surfaces. 

 The other mucous membranes of the alimentary apparatus 

 become congested and abraded; the parenchyma of the 

 liver, kidneys, and other organs becomes markedly de- 

 generated, so that the urine becomes highly albuminous 

 and very scanty in consequence of the anhydremia. The 

 cardio-vascular, nervous, and respiratory systems present 

 no characteristic changes. 



Intraperitoneal injection of the virulent cultures produces 

 fatal peritonitis in guinea-pigs. 



Supposing that the lower animals were immune against 

 cholera because of the acidity of the gastric juice, Nicati 

 and Rietsch, Van Ermengem, and Koch have suggested 

 methods by which the micro-organisms can be introduced 

 directly into the intestine. The first-named investigators 

 ligated the common bile-duct of guinea-pigs, and then 

 injected the spirilla into the duodenum with a hypodermic 



