NUTRITION 69 



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

 site energy by the oxidations which they accomplish as aero- 

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

 teria play an obviously 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 

 k organisms, the nitrates are soluble and enter the body only 

 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 by 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.]; The action of light is presumably that of a stimu- 



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

 stoffquellen bei der Ernahrung der nitrificierenden Fermente. (Polish) 

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

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



t Susuki, U. Uber die Assimilation der Nitrate in Dunkelheit. Botan. 

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

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

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



+ Godlewski, E. Zur Kenntniss der Eiweissbildung aus Nitraten in der 

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

 Laurent, E. Recherches experimentales sur Tassimilation de 1'azote am- 

 moniacal et de 1'azotte nitrique par les plantes superieures. Bulletin de 

 1' Academic Royale de Belgique, t. 32, 1896. Palladine, W. Influence de 

 la lumiere sur la formation des matieres proteiques actives et sur Penergie 

 de la respiration des parties vertes des vegetaux. 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.) 



