156 SPECIAL BACTERIOLOGY 



the same proportions as above. If in sixteen to twenty-four hours the 

 vibrioiies are rolled together in flakes at the bottom of the reagent 

 glass, and the upper portions of the fluid remain clear, then the 

 reaction is the same as that exhibited by the genuine cholera vibrio. 



Vitality. The comma bacilli do not exhibit much resistance. They 

 are destroyed in water heated to 52 C. in four minutes. They withstand 

 lower temperatures better ; in ice they lose their vitality in a few days. 

 The addition of 0'07 to 0'08 per cent, hydrochloric or nitric acid to 

 neutral culture media prevents their growth ; this explains why normal 

 gastric juice, which contains about 0'2 per cent, of hydrochloric acid, 

 exhibits an insurmountable obstacle to the cholera bacilli. When spread 

 in a thin layer and dried they lose the faculty of further development in 

 three hours. In moist surroundings under favourable circumstances 

 Koch's bacilli live a long time about nine months. In six months old 

 agar and gelatine cultures they sometimes still retain their vitality. 

 Weak solutions of the ordinary antiseptics kill the cholera bacillus very 

 quickly ; a J per cent, solution of carbolic acid kills them in a few 

 minutes. In the dejections of cholera patients the bacilli sometimes 

 remain alive for weeks, but this occurs only under extremely favourable 

 circumstances. The cholera bacillus multiplies to some extent in 

 sterilized river or well water, preserving its vitality in such water for 

 several months. In milk and water containing other bacteria it dies out 

 in a few days. In greatly diluted bouillon media the cholera bacilli may 

 take the precedence of the common saprophytic bacteria, forming upon 

 the surface of the medium the characteristic film. 



The comma bacilli only survive for a few days when mixed with 

 normal faeces. 



Pathogenesis. The introduction of cholera bacilli into the stomach 

 of man may cause 110 bad result, but sometimes a more or less intensive 

 diarrhoea results (self-infection by Pettenkoifer and Emmerich), and in 

 other cases genuine dangerous cholera with all the clinical symptoms. 

 A young doctor died in Hamburg of typical cholera, caused by a drop of 

 peritoneal exudate containing vibrio getting into his mouth during the 

 demonstration of PfeifFer's reaction. Subcutaneous injection with cholera 

 bacilli in man only causes local symptoms and slight fever. According 

 to Klemperer the blood thereby acquires immunizing properties. 



A disease resembling cholera can be produced in guinea-pigs by 

 direct introduction of the vibrio into the duodenum evading the stomach 

 and tying the gall-duct or by introduction of the bacilli into the 

 stomach, previously rendered alkaline with a solution of soda, and at the 

 same time injecting 2 to 3 c.c. of tincture of opium into the peritoneal 

 cavity. Tying the gall-duct and injecting tincture of opium into the 

 peritoneal cavity interrupts the peristaltic action of the bowels. 



Bacteriological Diagnosis. (1.) Microscopical Examination. 



