218 EXPERIMENT STATIOjST EECOED. 



In the separation of flagellates from ciliates an 8-day-old culture of soil organ- 

 isms was used which was prepared by adding 100 gm. of clay-loam soil to 1 

 liter of a 10-per cent hay infusion plus 0.5 per cent egg albumin. The numbers 

 of protozoa in the culture solution were counted, and 10 cc. of the solution was 

 then allowed to filter through from one to five thicknesses of sterilized filter paper 

 and the filtrate incubated for 5 days at 22° C. It was found that large ciliates 

 were not able to pass through filter paper at all. The numbers of small ciliates 

 decreased rapidly on increasing the thicknesses of filter paper from two to four. 

 Thus, with four thicknesses of filter paper all the ciliates in the solution were 

 separated from the flagellates and the small ciliates were easily separated from 

 the large ciliates. With five thicknesses of filter paper it was found that 90 

 per cent of the bacteria in the original solution had passed through the filter, 

 thus leaving the protozoan residue comparatively free from bacteria. 



A list of references to literature bearing on the subject is appended. 



A review of work on. soil inocvilation, J. Golding and H. B. Hutchinson 

 (Rpt. Brit. Assoc. Adv. Sci., 1914, p. 668). — In this brief review it is stated that 

 " experience has shown that it is not suflicient to have a pure and active culture 

 in order to attain success in soil inoculation, but that the soil itself shall be suit- 

 able for the growth and continued existence of the introduced organism, and 

 that the supply of mineral nutrients shall not be the limiting factor in the 

 growth of the plant. . . . Comparative work with pure cultures and inoculation 

 by means of soil which has previously carrie<l a specifieil leguminous crop has 

 shown in the majority of cases the superiority of the latter, and cultivation 

 in the laboratory has latterly included the use of soil media or soil itself since 

 the organism appears to retain its power of infection to a greater extent in 

 this than in other media. The use of pure cultures possesses advantages on the 

 score of cheapness and convenience, . . . and recent work especially has shown 

 the danger attending transference of plant diseases in soil used for legume in- 

 oculation. The relations attending infection of the plant and subsequent mutual 

 existence are very complex, and future experimental work in preparing cultures 

 must aim at reproducing these conditions in order to permit of the production 

 of cultures in active growth and possessing great virulence." 



The nitrifjring' powers of soils as indices to their fertility, C. B. Lipman 

 (Proc. Soc. Prom. Agr. Sci., 35 (1914), pp. 73-79).— In a general discussion of 

 this subject the author cites cases of uneven growth of barley on two fields, one 

 of silt loam and the other of humus loam soil. In both cases the better growth 

 was associated with a higher nitrifying iwwer of the soil. From the.'^e and 

 other observations he concludes that the nitrifying power of a soil is one of 

 the prime factors in determining its productive power. 



Free nitrogen and the higher plants, M. Molliabd {Coinpt. Rend. Acnd. Sci. 

 IPari^'i, 160 (1915), No. 9. pp. 310-313; abs. in Rev. Sci. [Paris], 53 (1915), I, 

 No. 8, p. 127). — In experiments with radishes under rigorously aseptic condi- 

 tions results were obtainetl from which the author concludes, with Boussingault. 

 that this plant is incapable of utilizing the free nitrogen of the air. 



Bacterial toxins in soils, R. Greig-Smith (Rpt. Brit. Assoc. Adv. Sci., 1914. 

 pp. 667, 668).— The substance of this article has been previously noted from 

 another source (E. S. R., 31. p. 620'). 



A systematic scheme for experimental work with fertilizers, A. T. Stx'art 

 (Proc. and Trans. Roy. Soc. Canada. 3. scr.. 8 (1915), Sect. III. pp. 167-176. 

 pi. 1, figs. 3; ahs. in Chem. Abs., 9 (1915), No. 17. p. 2^/8).— This article em- 

 phasizes the fact that the number of factors influencing the action of fertilizers 

 is so great as to make it diflicult to draw general deductions. The meaning of 

 the law of minimum as applied to fertilizers is discussed and curves iilusti-Mtins 

 the law are given. 



