CHOLERA VIBRIO 567 
it as indol derivative. It is jH-obable that Brieger's exi)lanati()n is the 
correct one. The substance formed is nitroso-indol, the indol radical 
being deri\'ed from the decomposition of tryptophan. The same reac- 
tion may be obtained from the rice-water stools of cholera patients. 
The cholera-red reaction is not produced in media containing iitilizable 
carbohydrates.^ 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. 
Greig- has found that many cholera-like vibrios isolated from water 
and from the feces produce the typical nitroso-indol reaction in peptone 
w^ater. In addition to nitroso-indol, cholera vibrios })roduce consider- 
able amounts of ammonia and hydrogen sulphide in sugar-free media. 
The addition of utilizable carbohydrate reduces deaminization and 
other evidences of extensive proteolysis, in cultures of cholera vibrios, to 
a minimum.^ The products of the fermentation of utilizable carbo- 
hydrates are chiefly acids; of these levolactic acid^ and, to a lesser 
degree, acetic and butyric acid are the most abundant.^ 
All true cholera vibrios produce acid in glucose; a majority form acid 
from lactose. Saccharose is somewhat less constantly fermented. It 
is possible that several strains exist, some of which may be identified 
partly by their utilization of the more common carbohydrates. 
Toxin.— The nature of the poison or poisons produced by the cholera 
vibrio is still a subject of controversy, although the disease Asiatic 
cholera appears to be a toxemia, because the organisms do not com- 
monly invade the tissues of the patient, even in fatal cases. Indeed, 
cholera vibrios injected into the tissues appear to migrate toward 
the alimentary canal. Castellani'^ has prepared an endotoxin by digest- 
ing cholera vibrios with pancreatin. The cytoplasm of the organisms 
appears to be practically unchanged, solution of the ectoplasm alone 
resulting from this process. The toxicity of this preparation upon 
intravenous injection is approximately the same as that of the 
unchanged vibrios, but intraperitoneal injections are less toxic. 
MacFadyean^ has prepared an endotoxin from frozen and finely 
ground cholera vibrios which upon injection into experimental animals 
leads to a great gastro-intestinal disturbance, and the passage of large 
amounts of water, salts (especially sodium salts) and later organic 
substances from the blood to the intestines. The blood is thereby con- 
centrated (sp. gr. even to 1.075), the erythrocytes and leukocytes are 
consequently apparently— although not actually— increased, and the 
alkali of the body is materially depleted. Pfeiffer^ believed that the 
1 Gorini: Centralbl. f. Bakteriol., 1893, 13, 790. Kendall: Boston Med. and Surg. 
Jour., 1913, 168, 825. 
2 Indian Jour. Med. Research., 1917, 5, No. 1. 
3 Kendall, Day and Walker: Jour. Am. Chem. Soc, 1913, 25, 1240. 
4 Gosio: Arch. f. Hyg., 1894, 21, 114; 1895, 22, 1. 
5 Kuprianow: Ibid., 1893, 19, 282. « Compt. rend. Acad. Sci., 1919, 168, 578. 
" Centralbl. f. Bakteriol., orig., 1906, 42, 365. 
" Ztschr. f. Hyg., 1892, 11, 393; 1895, 20, 198. 
