Specificity 505 



needle, with the result that the animals usually died, some- 

 times with choleraic symptoms. The excessively grave 

 nature of the operation upon such a small and delicately 

 constituted animal as a guinea-pig, however, greatly lessens 

 the value of the experiment. Koch's method of infection 

 by the mouth is much more satisfactory. By injecting 

 laudanum into the abdominal cavity of guinea-pigs the 

 peristaltic movements of the intestine can be checked. The 

 amount necessary for the purpose is large and amounts to 

 about i gram for each 200 grams of body-weight. It 

 completely narcotizes the animals for a short time (one to 

 two hours), but they recover without injury. The contents 

 of the stomach are neutralized after administering the 

 opium, by introducing 5 c.c. of a 5 per cent, aqueous solution 

 of sodium carbonate through a pharyngeal catheter. With 

 the gastric contents thus alkalinized and the peristalsis 

 paralyzed, a bouillon culture of the cholera spirillum is 

 introduced through the stomach- tube. The animal recovers 

 from the manipulation, but shows an indisposition to eat, 

 is soon observed to be weak in the posterior extremities, 

 subsequently is paralyzed, and dies within forty-eight hours. 

 The autopsy shows the intestine congested and filled with 

 a watery fluid rich in spirilla an appearance which Frankel 

 declares to be exactly that of cholera. In man, as well 

 as in these artificially infected animals, the spirilla are 

 never found in the blood or tissues, but only in the intestine, 

 where they frequently enter between the basement mem- 

 brane and the epithelial cells, and aid in the detachment of 

 the latter. 



Issaeff and Kolle found that when virulent cholera spirilla 

 are injected into the ear-veins of young rabbits the animals 

 die on the following day with symptoms resembling the 

 algid state of human cholera. The autopsy in these cases 

 showed local lesions of the small intestine very similar to 

 those observed in cholera in man. 



Guinea-pigs are also susceptible to intraperitoneal injec- 

 tions of the spirillum, and speedily succumb. The symp- 

 toms are rapid fall of temperature, tenderness over the 

 abdomen, and collapse. The autopsy shows an abundant 

 fluid exudate containing the micro-organisms, and injection 

 and redness of the peritoneum and viscera. 



Specificity. The cholera spirillum is present in the de- 

 jecta of cholera with great regularity, and as regularly absent 



