518 EXPERIMENT STATION RECORD. 



ject reported np to the end of 190G. The review has been prepared with the 

 hope that it "may serve to call attention to the progress already made, to indi- 

 cate the possibilities of the subject and to stimulate further and broader inquiry 

 in this important held in this country." The subject is discussed under the fol- 

 lowing heads: ^Methods, bacterial decomposition of nonnitrogenous organic 

 substance, transformation of mineral constituents of soil, chemical phases of 

 decay and putrefaction, ammoniflcation, oxidation processes in the soil, nitrifi- 

 cation, deoxidation processes in the soil, denitrification. bacterial synthesis of 

 nitrogenous compounds, nitrogen fixation (nonsymbiotic and symbiotic fixation 

 and soil inoculation), and unsolved jiroblems. 



Studies on the bacterial content of air and soils of the Antarctic region, 

 E. Ekelof (Ztsclu: Hug. u. Infcktiomkrank., 56 (1907), No. 3, pp. S.'iJi-SlO, dijin. 

 1). — Observations made during the Swedish South Polar Expedition of 1901- 

 1904 are reported, showing a rather large and varied bacterial flora in the upper 

 layers of tlie soil during the warmer months of the year but a very limited 

 bacterial content, in the air of the Antarctic regions. 



Experiments on the formation of nitric acid in soils, E. Murmann {Osterr. 

 Chcm. Ztg., 10 (1901), Xo. IS, p. 181: abs. in Chcin. ZentbL, 1907, II, No. 8, p. 

 62.'f). — Experiments on a small scale are reported in which soil from which 

 lime had been extracted by treatment with hot hydrochloric acid was mixed 

 with varying amounts of calcium carbonate (0.1 to 2 per cent) and the amount 

 of nitrates formed in 15 days at 12 to 16° C. determined. The residts show that 

 the addition of 0.1 per cent of calcium carbonate very greatly increased the 

 nitrate formation in the soil. The addition of as much as 2 per cent of cal- 

 cium carbonate, however, resulted in a slight decrease in the rate of nitrate 

 formation. % 



The fixation of nitrogen by the nodule former, K, (iREic-SMixH (Jour. Soc. 

 Vhc))i. Indus., 26 (1907), No. 7, pp. SOJi-306 ; ahti. in Jour. Client, tifjf. [London], 

 92 (1907). No. 536. II, p. 1/98). — Studies of various tubercle bacteria and nitro- 

 gen-fixing bacteria under different conditions are rei»orted. 



Nitrogen-fixing bacteria were found not only in the root tubercles but in the 

 stems of plants. The organisms found in the tubercle produced a nitrogenous 

 slime which was assimilated by the plant on which the tubercles occurred. 

 Those living in the more acid stem, however, did not produce this nitrogenous 

 slime. When transferred to artificial media the tubercle organisms exhibit dif- 

 ferences in their slime- forming cai)acities. " Some do not produce it upon any 

 kind of artificial medium, others do not do so immediately, but may be induced 

 to form it by repeated and rapid transference ujiou suitable pabula. The 

 majority form more or less slime upon all kinds of saccharin media, but a few, 

 while producing it upon artificial media with a plant basis (e. g., saccharose 

 bean-agar), refuse to do so upon an entirely synthetic medium." The author is 

 of the opinion that the formation of root tubercles need not be considered a 

 i-esult of irritating parasitic action but rather as a consequence of the produc- 

 tion of nutrients at that place resulting in better nourishment and growth of 

 the cells than in other parts of the roots. It was found that dextrose, levulo.se, 

 saccharose, maltose, and mannite furnished a good source of carbon for the 

 organisms, but that lactose was a very poor nutrient. It is therefore believed 

 that the use of whey as the basis for the preparation of a medium for cultures 

 of such organisms would lead to disappointment, thus explaining the nnsatis- 

 factory results which have been obtained with commercial cultures prepared 

 by the whey-gelatin method employed by European firms. 



The organisms from the nodules of peas at different times were ajiparently 

 identical but in case of blue lupines were very variable. 



