AGRICULTURAL BOTANY. 425 



nitrate destruction by these bacteria when present and other conditions are 

 favorable. 



The most divergent denitrifying organisms appear to act in the same ways on 

 exclusion of oxygen. Simultaneously with the admission of air an increase ol 

 proteins occurs with coincident increase of energy i-equirement. The most 

 diverse experiments indicate that the degree of air access did not affect the 

 relation between synthesis and use of energy material. 



The 3 bacteria studied do not show the same activity and nitrate require- 

 ment per unit of energy material used. The optimal relation between the 

 carbon and the nitrate used is for the 2 stronger bacteria (B. pyocyaneus and 

 B. fluorescens liqucfaciens) 1 per cent dextrose to l.G per cent potassium 

 nitrate. Reduction of nitrate supply far below that of carbon greatly reduces 

 the intensity of the process. All of these 3 kinds of bacteria use carbon the 

 more freely as more individuals are present. With a sugar concentration of 

 more than 1 or 2 per cent, a depression of denitrification occurs, as thereby 

 (through the building of fatty acids) the development of the denitrifying 

 bacteria is retarded. The increase of alkaline carbonates has the opposite 

 effect. Increased concentration of dextrose within limits is accompanied by its 

 increased employment as a source of energy. 



These experiments confirm the findings of Koch and Pettit and of Marr 

 (E. S. R., 23, p. 430) that in the soil, under otherwise favorable conditions of 

 moisture, etc., a loss of nitrates may still occur. No certain explanation is at 

 hand, but the suggestion is made that an increased production of carbon dioxid 

 and the indirectly produced exclusion of air may in part account for the de- 

 struction of nitrates observed. 



It is suggested also that an explanation may now be expected of the very 

 different results obtained by investigators, and that a point of departure for 

 Investigations of great importance has been reached. 



Metabolism and translocation in young foliage trees, H. Bauer (Naturw. 

 Ztschr. Forst u. Landiv., 9 (1911), No. 9, pp. -} 09-4 i 9). —This is a further ac- 

 count of the author's investigations of the nutritive changes in young trees 

 (E. S. R., 25, p. 27). This reiwrt gives detailed and tabulated particulars of 

 changes (expressed in percentages) observed in the study of the second year's 

 growth of ash trees during the four successive periods of about SO, 50, 70, and 

 60 days, extending from Februai'y 27 to November 17. 



The periodicity of nutritive processes in young beeches, W. Kxjbleb 

 (Naturw. Ztschr. Forst u. Landw., 10 (1912), No. 4-5, pp. 161-181, figs. 2).— 

 This is contributory to the work of E. Ramann (E. S. R., 2G, p. 4-13; 27, p. 229) 

 and of 11. Bauer (see above). The author investigated the seasonal changes 

 occurring in beeches of 2 years' growth as regards nutritive requirements, 

 the formation of dry substance, etc., in the plants. The results are given in 

 tabular form of analyses made of the whole plant, of stem and root, together 

 and separately, and of the leaves. 



The results as regards the whole plant, which are graphically represented, 

 show that phosphoric acid, nitrogen, potash, lime, and magnesia (which fol- 

 low mucli the same general course but show individual differences) all decrease 

 until early in May. The percentages then rise sharply until about the middle of 

 September when a decline almost as steep sets in, reaching by November ap- 

 proximately the same levels as about the middle of July. The curves are 

 xery much steeper in case of those plants grown under the more favorable 

 conditions. 



The periodicity of synthetic processes in young foliage trees, H. Baueb 

 (Naturw. Ztschr. Forst u. Landw., 10 (1912), No. 4-5, pp. 188-199).— This is a 

 report in continuation of the work carried on by this author, E. Ramann, and 



