LIBERATION OF NITROGEN, AND DE-NITRIFICATION 235 



the infected animal body is manifested as disease, .so also the former can elaborate 

 substances having a poisonous effect on the parasitic micro-organisms. The 

 normal and continuous presence of such protective albuminoids, or alexines, as 

 they are called, in the blood, is the cause of the natural immunity enjoyed by 

 certain animals against certain pathogenic species .of bacteria. A closer con- 

 sideration 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 pro- 

 vides 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 nitro- 

 genous 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 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 the loss of nitrogen may occur, 

 not only as a result of its liberation in a free gaseous state, but also in conse- 

 quence 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 Eumycetes), 

 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 vulgalus, 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 : Aspergilhis terricola, Penicillium glaucum, P. 

 cladosporioides, Mucor mucedo, M. racemosus, Botrytis cinerea, B. vtdgaris, Cephalo- 

 thecium roseuni, 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 albumen, leucine, and tyrosine, 

 but does not attack urea. The losses occasioned by the volatilisation of ammonia 

 produced in this manner may be very considerable, but will not be further 

 considered here. We will now turn to the liberation of uncombined nitrogen. 



The first researches on this point were undertaken by JULES REISET (I.) in 

 1854 and 1855. He asserted that free nitrogen is always evolved during the 

 putrefaction of manure, whilst G. HUFNER (I.) arrived at the contrary opinion, 

 being unable to discover any liberation of free nitrogen when atmospheric air 

 or pure oxygen was led through the putrefying substances. The same result 

 was obtained by ALEXANDER EHRENBERG (I.), 0. KELLNER and T. YOSHII (I.), and 

 BR. TACKE (I.) ; and this view was also held by H. IMMENDORPF (II.) in 1893. 



