THE NITRIFYINO BACTERIA. 375 



only over the surface of the medium, then the mixture 

 must first be allowed to solidify. 



By the use of this silicate-gelatin Winogradsky has 

 isolated from the gelatinous film in the bottom of fluids 

 undergoing nitrification a bacillus which he believes to 

 be associated with the nitro-monas in the nitrifying 

 process. 



Our knowledge of these organisms is as yet too in- 

 complete to permit of a satisfactory description of all 

 their morphological and biological peculiarities. What 

 has been said will serve to indicate the direction in 

 which further studies of the subject should be prose- 

 cuted. 



For further details the reader is referred to the 

 original contributions.* 



In addition to the bacteria concerned in putrefac- 

 tion and nitrification there are occasionally present in 

 the soil micro-organisms possessing disease-producing 

 properties. Conspicuous among these may be men- 

 tioned the bacillus of malignant oedema (vibrion aep- 

 tique of the French), the bacillus of tetanus, and the 

 bacillus of symptomatic anthrax [Rausehbrand, Ger- 

 man ; charbon symptomatique, French). It is some- 

 times due to the presence of one or the other of 

 these organisms that wounds to which soil has had 

 access (crushed wounds from the wheels of cars or 

 wagons, wounds received in agricultural work, etc.) 

 are followed by such grave disturbances of the con- 

 stitution. 



' Winogradsky: Annalesderin8titutPasteur,toinesiv., 1890, and v., 1891. 

 Jordan and Sicharde : Eep. State Board of Health, Mass. " Purification 

 of Sewage and Water." 1890, vol. ii. p. 864. 



Frankland, O. C. and P. F. : Proc. Eoyal Soc. London, 1890, xlvii. 



