CHOLERA VIRUS. 147 



originated from the cells of the vibriones and was of a nucleic 

 character. In addition to this, however, the cultivations con- 

 tained a poison, a nucleo-albumin, which was unstable when 

 heated; it occurred in the cultures that had been sterilised at 

 58 C., while the filtrates were only very slightly poisonous. It 

 produced very violent diarrhoea and other choleraic symptoms. 



WASSERMANN 1 found that the dead cells when used in the 

 proportion of eight to ten times the quantity of the living 

 vibriones produced the typical symptoms, ending in death, in 

 a guinea-pig. By evaporation of the cultures and precipitation 

 with alcohol he obtained a poison which, in a dose of 0*02 grm., 

 killed guinea-pigs but produced no antitoxic immunity. PFEIFFER 

 and WASSERMANN 2 and ISSAEFF S assert that the serum of im- 

 mune animals does not confer antitoxine immunity. KLEMPERER* 

 found filtered cultivations to be slightly poisonous. 



The question was then further investigated by WESBROOK. 

 He cultivated the vibriones on alkali albuminate which gave 

 no biuret reaction. After three weeks there was an unmis- 

 takable biuret reaction. The poison, when filtered through 

 porcelain, was fatal to guinea-pigs in doses of 0'5 to T5 c.c. 

 and possessed immunising capacity. 



He attempted to isolate it by neutralising the alkali albu- 

 minate with hydrochloric acid so that it was precipitated, 

 concentrating the filtrate in vacuo at 40 C., and dialysing it 

 after the addition of alcohol. Both the precipitated albuminate 

 and the albumose left in the filtrate were poisonous. 



He also obtained from a rich growth of the bacteria in proteid- 

 free culture-media (like those employed by USCHINSKY), to which 

 a certain proportion of sodium hydroxide had been added, a 

 poison which, after imperfect purification, yielded a brown sub- 

 stance that gave no biuret reaction and only a faint xantho- 

 proteid reaction. It had a poisonous action and immunising 

 capacity. From these results he concluded that cholera virus 

 was only in combination with proteids, but was not a proteid 

 itself. 



This poison was invariably only sparingly produced in the 

 cultivations, and was but very slightly poisonous in comparison 



1 Wassermann, " Unt. iib. Immun. geg. Choi, asiatica," Zeit. f. Hyg., 

 xiv., 35, 1893. 



2 Pfeiffer and Wassermann, " Unters. iib. das Wesen d. Choleraimmuni- 

 tat," Ze.it. f. Hyg., xiv., 46, 1893. 



3 Issaeff, "Unt. lib. d. kiinstl. Imm. geg. Cholera," Zeit. f. ffyg.,xv., 

 287, 1894. 



4 Klemperer, " Schutzimpf . d. Menschen geg. asiat. Cholera," Berl. Uin. 

 Woch., 1892, 970. 



