132 ATLAS OF BACTERIOLOGY. 



urese and bacillus fluorescens) produced ammoniacal 

 decomposition of urine. 



Among sixty varieties only three (bacterium vul- 

 gare, bacterium prodigiosum, and bacterium kiliense) 

 developed a distinct ammoniacal odor in sterilized 

 human urine. 



Leube employed Jacksch's nutrient solution : In 1 

 litre 0.125 acid potassium phosphate, 0.062 mag- 

 nesium sulphate, 5 gm. Seignette salts, which were 

 sterilized . by boiling. To the sterile solution he 

 added 3 gm. urea which had been sterilized in a dry 

 state at 106 (boiling of urea solutions is to be 

 avoided because a part of the urea is thus converted 

 into ammonium carbonate) . In order to demonstrate 

 the presence of the ammonia Leube employed Ness- 

 ler's reagent, a very sensitive test. For the study 

 of the quantitative relations vide Brodmeier (C. B., 

 XVIII. , p. 380). Urea is not decomposed upon a 

 nutrient medium which contains sugar. Burri, Her- 

 feldt, and Stutzer (C. B., Pt. II., Vol. I., 284) recently 

 described three rods which decompose urea very 

 vigorously. 



In addition to ammonia Brieger's investigations 

 have disclosed a large number of basic crystalline 

 nitrogenous bodies as products of bacterial metab- 

 olism. These bodies are now usually called pto- 

 mains (^rcD^a, putrefaction) or putrefaction alkaloids, 

 when they are not poisonous, and toxins* when they 

 are poisonous. 



* With the growth of our knowledge of bacterial poisons the 

 conception of toxins has been enlarged, so that now the major- 

 ity of writers call all bacterial poisons toxins, irrespective of 

 their chemical constitution. 



