PUBLICATIONS ON AGRICULTURAL BOTANY IN FRANCE. 849 



and the organisms which produce ammonia are capable of continuing? 

 their activity, the fungi having removed the ammonia which checks or 

 destroys the activity of the organisms producing it. These conclu- 

 sions show the complexity of the phenomena produced hy the organ- 

 isms of the soil and the difficulty of regulating them. 



The reduction of nitrates in arable soils has been studied by Breal,' 

 and according to him the simple settling of soil should transform it 

 from a nitrifying to a denitrifying medium, and inversely the addition 

 of vegetable substances by lightening and separating the soil should 

 increase the activity of nitrifying organisms. It has been found, how- 

 ever, that, on account of the so-called straw ferment,- the addition 

 of straw to the soil may result in denitritication. This is also the opin- 

 ion of Wagner-' concerning the activity of denitrifying ferments. The 

 experiments of Pagnoul and l)eh<''rain are in the same line. 



Among the investigations of the chemical phenomena owing their 

 action to the intervention of soluble ferments produced by the plant 

 may be mentioned the work of Bertrand* on the latex of Eh us spp., on 

 laccase and its oxidizing power,^ and the investigations on the occur- 

 rence of laccase in plants.'' He found laccase in the roots of beets, 

 carrots, turnips, and dahlias; in the tubers of potatoes and artichokes; 

 in the leaves of clover, beets, alfalfa, etc., and in the fiuit of apples, 

 (juinces, etc. 



This widely distributed ferment has also been studied by Bourqnelot,' 

 who has shown that laccase is a new type of diastase characterized by 

 its strong oxidizing i)Ower, this i)roperty explaining the formation of 

 certain perfumes of plants. The role of oxidizing ferments" is very 

 important from the .standpoint of the chemical dynamics of the plant, 

 and is a subject worthy of extended study. 



De Key Pailhade^ has shown the simultaneous existence of two 

 oxidizing ferments, the laccase of Bertrand, which oxidizes tincture of 

 guaiacum, and the ferment of Kohman and Spitzer, which produces 

 indophenol in the presence of naphthol and paraphenylenediamiu in 

 solution. 



Bertrand and Mallevre '" have shown the occurrence of pectase in the 

 plant world. It would be of interest to pursue further the (piestiou of 

 vegetable digestion as suggested by the work of V. Toulet." 



' Ann. Agron., 22 (1896), p. 32 (E. S. R., 7, p. 663). 



•' Compt. Rend., 114 (1892), p. 681 (E. S. U., 3, p. 916). 



='Deiit. lundw. Presse, 22 (189.->), pp. 91, 98, 123. 



* Compt. Keiul., 118 (1894), p. 121.5. 



^' Compt. Keud., 120 (189.-)), p. 266. 



e Compt. Reml., 121 (189.->), p. Ifit!. 



■ Bui. See. Biol., ser. 10, vol. 3, p. '.U'>. 



«Ann. A},non., 22 (1896), p. 116. 



''Assoc. Vv. Av. .Sci., Conjures dc ('nitliiifjo, 1896, p. l.")3. 



'" Moniteur Quesiievillc, 12 ( 1X96), jt. 21.">. 



" Comi)t. Kend., 123 (1896), p. :!r)6. 



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