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A MANUAL OF BACTERIOLOGY 



grows remain perfectly clear, (b) The microbe has 

 the remarkable capacity of indefinite growth in a 

 medium devoid of organic matter, (c) It is O8 fju 

 in length, and hardly longer than broad, hence it 

 has been called a bacillococcus. It occurs both 

 isolated, in pairs, and in small irregular groups, (d) 

 In the living state it exhibits a vibratory movement 

 only, (e) The microbe cultivated in ammoniacal 

 solutions converts the ammoniacal into nitrous 



nitrogen, and not into 

 nitric nitrogen. (/) 

 The same microbe ap- 

 pears to grow in broth 

 or bouillon, but not on 

 solid gelatine-peptone. 



(2) Winogradsky 's re- 

 searches. Winogradsky 

 has also obtained a 

 similar bacillus to that 

 of Frankland, which 

 grows in an inorganic 

 ammoniacal solution, but 



not on gelatine - peptone ; and he has shown 

 that this microbe grows (and may be isolated) 

 on the surface of gelatinous silica containing the 

 inorganic ammoniacal salts already mentioned. 

 This nitrifying microbe gives rise to very charac- 

 teristic colonies on gelatinous silica. Winogradsky's 

 bacillus measures from 1-1 to 1-8 ^ long, and does 

 not exceed 1 //, broad. This microbe occurs singly, 

 in pairs, rarely in chains of three to four individuals, 

 and as zooglcea. It converts ammoniacal into 



FIG. 58. MICROBES OF NITRIFICATION. 



A, Frankland's nitrous bacillus. 



B, Warington's nitric micrococcus. 



