504 THE CHOLERA GROUP 



the indol radical being derived from the decomposition of- tryptophan. 

 The same reaction may be obtained from the rice water stools of 

 cholera patients. The cholera-red reaction is not produced in media 

 containing utilizable carbohydrates. 1 The nitroso indol or cholera-red 

 reaction is not specific for the cholera vibrio. Other closely related 

 bacteria also give the same reaction. On the other hand, not all true 

 cholera vibrios form nitroso indol. 



Besides nitroso indol, cholera vibrios produce considerable amounts 

 of ammonia and hydrogen sulphide in sugar-free media. 2 All true 

 cholera vibrios produce acid in dextrose and lactose. The production 

 of acid in saccharose and mannite is somewhat less constant. The 

 acids produced are levolactic acid, 3 also acetic and butyric acids. 4 



Toxin. The nature of the poison or poisons produced by the cholera 

 vibrio is still a subject of controversy, although the disease cholera 

 appears to be a toxemia, for the organisms do not commonly invade 

 the tissues of the body even in fatal cases. Pfeiffer's view 5 was that 

 the toxin is an endotoxin which is liberated by autolysis from the 

 organisms themselves. Behring and Ransom, 6 on the contrary, 

 claim to have separated a soluble toxin from broth cultures of true 

 cholera vibrios which in doses of about 0.5 c.c. will kill guinea-pigs in 

 twenty-four hours. They further claim to have immunized guinea- 

 pigs and goats to the toxin by injecting gradually increasing doses. 

 The antitoxin thus obtained protects non-immune animals against 

 the toxin or from infection with living cholera vibrios. The toxin is 

 unaffected by moderate heat, chloroform, toluol, or carbolic acid. 



Metchnikoff Roux and Taurelli-Salimbini 7 enclosed peptone cul- 

 tures of cholera vibrios in collodion sacs which were placed in the 

 peritoneal cavities of guinea-pigs. As controls, killed cultures of 

 cholera vibrios and sterile uninoculated peptone respectively were 

 placed in other guinea-pigs in collodion sacs. The guinea-pigs which 

 received only sterile peptone solution in capsules failed to show 

 symptoms; those containing killed cultures of cholera vibrios in 

 capsules showed a slight febrile reaction and some emaciation; the 

 guinea-pigs which received the collodion capsules containing living 

 cholera vibrios died after three to five days with symptoms of choleraic 



1 Gorini, Centralbl. f. Bakt., 1893, xiii, 790. Kendall, Boston Med. and Surg. Jour., 

 1913, clxviii, 825. 



2 Kendall, Day and Walker, Jour. Biol. Chem., 1913, xxxv, 1240. 



3 Kuprianow, Arch. f. Hyg., 1893, xix, 288. 

 "Gosio, Arch. f. Hyg., 1894, xxi, 120; 1894, xxii, 11. 



6 Centralbl. f. Bakt., Ref., 1892, xi, 568. Ibid., 1895, xviii, 314. 



7 Ibid., 1890, xx, 627. 



