CONTAINED IN PLANTS FOR ANIMALS AND MEN. 477 



exist numerous kinds of bacteria which can reduce the nitrates to 

 the poisonous nitrites while other kinds of bacteria again reduce 

 them directly to the less noxious ammonia. (,) 



The dangerous character of nitrites is clearly elucidated 

 by the observation of Atkinson, that 0.2 g. sodium nitrite pro- 

 duces heavy intoxication in men.' 2 ' Guinea-pigs are killed by 

 0.5 g. of sodium nitrite no matter whether administered through 

 the stomach or subcutaneously, under the phenomena of paralys- 

 is and kyanosis. 



Of those bacteria which produce nitrites from nitrates, the 

 bacillus of Cholera asiatica acts most energetically, and Ennnericli 

 and Tsnboi have therefore propounded the theory that the 

 symptoms in cholera disease are due to the nitrites formed by 

 this bacillus in the intestines of men from the nitrates in food. a) 

 Indeed, this theory explains thus far alone the temporal, local 

 and individual disposition for cholera. (4) Pettenkofer pointed out 

 that cholera in temperate zones makes its appearance as a great 

 epidemic always late in summer or at the beginning of autumn, 

 further that certain cities are never visited by this epidemic, and 

 that drinking ivatcr has no influence upon the spread of cholera/ 5 ' 

 and inferred that there must exist a second principle besides the 

 cholera bacillus to make the genuine cholera possible. 



( 1 ) Id this regard an observation made by Richter is of great interest ; he discovered 

 nitrites in the urine in a case of acute affection (catarrh) of stomach and intestines, and 

 elucidated further that the action of a coccus upon the nitrates of the food had given rise 

 to the production of the poisonous nitrites. (Fortschritte. d. Med. 13. 478). 



(2) Certain animals as rabbits require more to affect them seriously ; perhaps there 

 exists conditions in them by which the nitrous acid is prevented from being set free so 

 easily. 



(3) Munch. Med. Wochenschr, 1893. That theory was attacked by Klemperer and 

 Pfeiffer, but not disproved. By means of the reaction of Cries, nitrous acid would no 

 doubt be discovered more often than formerly in the feces of cholera patients. 



For the production of the cholera-red reaction indol is necessary, but as Govini 

 (1893) has shown this is not formed in presence of much sugar and is absent sometimes 

 in cholera-feces. 



(4) Semerad came to the same conclusion as Pettenkofer, that besides meteorological 

 conditions the soil has also great influence, as his investigations on the cholera-epidemic 

 in Juugbwizlau left no doubt on this point. 



(5) The nitrates are present, if at all, in too small quantities to be taken into 



account : thus, the sum of nitrous and nitric acid in 10,000 parts of drink water of Tokyo 



( 1 885 ) was found to be : 



Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. 

 0.002 0.004 0.158 0.173 0.2 1 1 0.128 0.156 0.163 0.162 0.152 0.110 0.009 



