3 o6 PHENOMENA OF PUTREFACTION. 



nity enjoyed by certain animals against certain pathogenic species 

 of bacteria. A closer consideration of this matter would, however, 

 be beyond the scope of the present work, though it must be 

 referred to, as throwing new light on the connection between 

 Bacteriology and Physiological Chemistry. Full information on 

 the subject of protective inoculation and serum therapeutics can 

 be gathered from the concise text-book prepared by HUEPPE (VI.), 

 which at the same time provides an introduction to the study of 

 Pathological Mycology. On this latter subject P. BAUMGARTEN (I.) 

 has written a reliable handbook which is hereby recommended to 

 food-stuff chemists and agriculturists. 



173. The Liberation of Nitrogen, and 

 De-nitrification. 



The interest with which the farmer regards the decomposition 

 of nitrogenous substances, both in the manure heap and in the 

 soil, always proceeds from the same desire : to know what becomes 

 of the nitrogen, and whether it is retained in the soil. 



The alterations suffered by the nitrogenous manurial constituents 

 derived from urine will be described in Chapters xxxii. and xxxvi., 

 and at present we are concerned merely with the putrefaction of 

 the albuminoids, &c., evacuated in the faeces. 



In the first place, it must be remarked that a loss of nitrogen 

 may occur, not only as a result of its liberation in a free gaseous 

 state, but also in consequence of the volatilisation of ammonia 

 produced by the action of micro-organisms on the albuminoid 

 matter of the manure. We are indebted to E. MARCHAL (I.) for 

 proving that the faculty of eliminating ammonia from albuminoids 

 is common to a great many fungi (both Schizomycetes and Eumy- 

 cetes), occurring in large numbers in the soil, and quite distinct 

 from the Schizomycetes effecting the conversion of urea. Among 

 the fungi (widely distributed and frequently discovered in the 

 soil) examined and recognised by MARCHAL (II.) as powerful 

 ammonia - producers, may be mentioned in the Schizomycetes 

 group : Bacillus mycoides, Fliigge ; B. fluorescens liquefaciens, 

 Fl. ; B. fluorescens putidus, Fl. ; B. subtilis, B. arborescens, B. 

 mesentericus vulgatus, Fl. ; B. mesentericus ruber, Fl. ; B. janthinus, 

 Zopf; Proteus vulgaris, H; Bacterium coli commune, Sarcina 

 lutea, Micrococcus roseus, Fl. ; M. flavus, Fl. ; M. candicans, 

 FL, &c. ; and in the Eumycetes group : Aspergillus terricola, 

 Penicillium glaucum, P. cladosporioides, Mucor mucedo, M. race- 

 mosus, Botrytis cinerea, B. vulgaris, Cephalothecium roseum, and 

 others. The potency of the different species varies, the largest 

 quantity of ammonia (0.8 gram per litre of nutrient solution) 

 being produced by Bacillus mycoides. This last-named fission 

 fungus, which was minutely examined by Marchal, decomposes 

 both albumin, leucine, and tyrosine, but does not attack urea. 



