SOILS FERTILIZERS. 1027 



" When based upon their relative susceptibility to decomposition, the ferti- 

 lizers used rank thus: blood meal, bran, bone meal, and pent. In other words. 

 Avlieie immediate effects are required, blood meal and bran are preferable; 

 but where the beneficial action of the fertilizers is to be m.iiiHaincd for several 

 years, bone meal and peat are better. 



"The use of anaerobic conditions has no advantaj,'{> over the aerobic metlioil. 

 but is, instead, far more difficult to manii)ulate." 



Observations on an important group of soil bacteria. Organisms related 

 to Bacillus subtilis, F. 1). Cukstkk (Dclinriirc sla. lijit. lHO.i, ihk .'li-UG. /i(/s. 

 I*). — This is a preliminary report on the morphohtiiy. cultural features, chem- 

 ical functions, classification, and description of this group of organisms which 

 is understood to include "those members of the genus Bacillus, as defined by 

 Migula. which produce spores, liquefy gelatin, and grow under aerobic condi- 

 tions." The investigations here reported covered a period of nearly 2 years 

 and involved the comparative study of a large innnber of cultures. 



On nitrogen assimilation by lower organisms, B. IIkinze (Laiulir. .Jahrb., 

 35 (I'JOG), A'o. 6', pp. 8S0-910). — Accounts are given of studies and discussions 

 of nitrogen assimilation by nitrogen-collecting bacteria (alinit and root-tubercle 

 bacteria), fungi, algie, and Azotobacter organisms. The importance of the 

 fixation of free nitrogen from the standpoint of practical agriculture is also 

 considered. 



There was practically no fi.xation of nitrogen by alinit and pure cultures of 

 root-tubercle bacteria in the experiments made by the author in media free 

 from and containing nitrogen. The same was true in culture experiments with 

 I'homa heUr, A.ipcrgiUus uiijcr, rciik-iUium glaucum. and Mucor stolonifcr. In 

 experiments with Dematium-like molds and yeasts obtained from ordinary cul- 

 tivated soil and of Streptothrix-like fungi from fallow soil there was some 

 fixation, but this is ascribed only indirectly to the organisms named in that 

 they are believed to have furnished food for other organisms which brought 

 about the fixation. This indirect action is due to supplying organic food and 

 also to the fact that the fungi dissolve lime phosphate, which favored the 

 growth of the nitrogen-fixing organisms. 



In culture experiments with Chlorella derived from ordinary cultivated soil, 

 fallow soil, and sandy soils there was no appreciable fixation of nitrogen. With 

 both pure and impure cultures of Nostoc there was decided fixation of nitrogen 

 when proper conditions of food, temperature, etc., were maintained. It was 

 observed in these experiments that both the blue-green and the chlorophyll- 

 green algjB elaborate glycogen, a very available source of energy for nitrogen- 

 fixing organisms. 



Culture experiments with diff(>ront .Vzotobacter organisms under a variety of 

 <-onditions led to the conclusion, among others, that dibasic and tribasic potassium 

 Iihosphate and dibasic calcium phosphate are especially favorable to the growth 

 of these organisms. The best results as regards temperature were obtained 

 at 20 to .30° C, although the organisms showed more or less activity at tem- 

 Iieratures as low as 8 to 10°. Increases of nitrogen, due to fixation by Azoto- 

 bacter organisms, of as high as 2r)0 to ^no per cent were observed in the experi- 

 ments reported. Pectin and pentosan substances were not as efiicient sources 

 of energy as sugar. 



It is explained how these organisms gradually build up protein compounds 

 from free nitrogen, and pot experiments are reported which show that the 

 nitrogen of this Azotobacter material is much less readily assimilated than 

 that of nitrate of soda. Field experiments on fallow soil are referred to as 

 indicating that decided fixation may be brought about under such conditions 



