SOILS FEETILIZEES. 621 



loam failed to show nitrifying powers commensurate with those shown with 

 ammonium sulphate, although the relationship as regarded other soil types was 

 quite consistent in both series. 



In tests of the effect of sand and lime on nitrification in heavy clay soils, a 

 sandy loam, and a light porous soil it was found that lime caused a marked 

 increase in nitrates, while sand failed to stimulate nitrate formation, particu- 

 larly in the clay soils. 



The org'anic nitrogen of Hawaiian soils, W. P. Keli.ey and Alice R. 

 Thompson {Jour. Amer. Chem. Soc, 36 (lOlIf), No. 2, pp. 42y-JfU) .—Brief 

 technical accounts are given of investigations more fully reported elsewhere 

 (E. S. R., 30. p. 419; .31, p. 11). 



Notes on some methods for the examination of soil protozoa, C. H. Martin 

 and K. R. Lewin {Jour. Agr. Sci. [England], 7 {1915), No. 1, pp. 106-119, 

 pis. 2). — The purpose of this paper is to outline the present knowledge of the 

 life of the protozoa in the soil and to describe certain methods which have been 

 found useful in work on the subject. 



The authors think it probable that there are always some free living pro- 

 tozoa present in an active state in even relatively dry, poor soils. " In manur- 

 ing on ordinary soil with farmyard manure a large number of protozoa are 

 introduced into that soil, and if the conditions of culture are such as to 

 necessitate a high water and a high manurial content the protozoa may well 

 get the upper hand to such an extent as to produce a well-marked deleterious 

 effect on the crop, resulting in the condition known as soil sickness. . . . The 

 nature of the protozoan fauna seems to vary to a certain extent with the soil 

 under examination. ... It is probably that the richer the soil and the higher 

 the water content at the time of examination, the greater the probability of 

 the dominant culture form being the dominant trophic form in the fresh 

 soil. ... Up to the present the dominant active fauna of the soil, as shown by 

 the fresh films, consists mostly of amoebfe, the camcebae, and small flagel- 

 lates. ... In this connection one point which requires further investigation is 

 the frequent prevalence of relatively large flagellates in soil culture (e. g., 

 Prowazekia and Copromonas), whereas in fresh films the only flagellates found 

 are very small monads. . . . 



"Another factor which must be reckoned with ... is the possibility that the 

 present methods for the examination of fre.sh soil films do not give a fair 

 account in regard to these large flagellates, which may be caught up by their 

 flagella amongst the soil particles." 



It is stated in conclusion that there appear to be three categories under which 

 the protozoan population of any soil at a given moment should be studied, i. e., 

 (1) the active fauna, (2) the cysts, and (3) the cultural fauna. "In the 

 immediate future better methods must be devised for the detection of the active 

 fauna, a complete study is needed of the possible seasonal variations which 

 might result in a transfer of certain forms from the resting fauna to the active 

 fauna, and a more careful study mu.st be made of cultural conditions, so that 

 it may be possible to cultivate at once any desired member of the active fauna 

 of a soil." 



Studies on soil protozoa, A. Cunningham {Jour. Agr. Sci. [England], 7 

 (1915), No. 1, pp. 49-74). — The work discussed in this paper is a continuation 

 of that previously reported (B. S. R., 31, p. 2G) and deals with (1) the dilution 

 method and its application to the enumeration of protozoa in soils, (2) the 

 effect of protozoa on the numbers of bacteria in ammonifying solutions and on 

 ammonification in solution tests, and (3) the effect of inoculations of protozoa 

 on the bacterial content of partially sterilized soils. 



