NUTRITION 69 



p. 43) and without the aid of light, obtaining the requi- 

 site energy by the oxidations which they accomphsh as aero- 

 bic organisms. * Unlike the purple-bacteria, the nitrogen bac- 

 teria play an obviouslj- important part in nature, preparing 

 from otherwise useless materials those compounds of nitro- 

 gen upon which the existence of all other organisms depends. 

 Like all other substances concerned in the nutrition of 

 organisms, the nitrates are soluble and enter the body onlj- 

 in solution in water. The nitrates, especially potassic ni- 

 trate, which seems to be the most useful of these compounds, 

 absorbed by the roots of land plants and through other 

 organs of floating aquatic plants, are transferred by diffu- 

 sion throughout the body. The elaboration of these into 

 organic compounds can probably be accomplished hj all 

 living plant-cells, but in higher plants, in which division of 

 labor is carried to a high degree, it is accomplished by 

 some cells and not by all, very likely in the leaves and 

 other green parts or in parts not far distant. The manu- 

 facture of nitrogenous foods is accomplished both in dark- 

 ness and in the deeper tissues, and also in the light and in 

 superficial tissues, f It is probable that light, and even 

 certain rays of light, favor the elaboration of nitrogenous 

 foods.J The action of light is presumably that of a stimu- 



" Godlewski, E. Tiber die Nitrification des Ammoniaks und die Kohlen- 

 stoffquellen bei der Ernahning der nitrificierenden Fermente. (Polish) 

 Reviewed in Centralblatt f. Bakteriologie, 2te Abth., n., p. 458. Well sum- 

 marized ia Fischer's Vorlesungen iiber Bakterien, p. 103, Eng. trans, p. 106. 



t Susuki, U. tJber die Assimilation der Nitrate in Dunkelheit. Botau. 

 Centralblatt, Bd. 75, p. 289, 1898. On the formation of proteids and 

 the assimilation of nitrates by phfenogams in the absence of light. Bul- 

 letin Vin., No. 5, Imperial University, College of Agriculture, Tokyo, 1898. 



X Godlewski, E. Zur Kenntniss der Biweissbildung aus Nitraten in der 

 Pflanze. Anzeiger der Akademie d. Wissenschaften, Krakau, March, 1897. 

 Laurent, E. Eecherches experimentales sur 1' assimilation de I'azote am- 

 moniacal et de I'azotte nitrique par les plantes superieures. Bulletin de 

 rAcademie Royale de Belgique, t. 32, 1896. Palladine, W. Influence de 

 la lumi§re sur la formation des mati§res protSiques actives et sur I'energie 

 de la respiration des parties vertes des vfigetaux. Rev. gen. de Bot., t. XI., 

 1899. Jost, L. Die Stickstoffassimilation der grunen Pflanzen. Biol. 

 Centralblatt, Bd. 20, 1900. (Review of subject, and a bibliography, 

 to date.) 



