420 EXPERIMENT STATION RECORD. 



Some notes on soil protozoa, C. H. Martin and K. R. Lewin (Phil. Trans. 

 Roy. Soc. London, Ser. B, 205 {1914), No. 315, pp. 77-94, pls. 2).— This paper 

 gives an account of protozoan organisms found in two different kinds of soil by 

 a special method devised by one of the authors. Three new species are de- 

 scribed, yahlkantpfia soli, Ammha cucuinis, and A. gobanniensis. 



" The main purpose of this introductory paper has not, however, been the 

 study of these amoebte from a specific point of view, so much as the proof which 

 we hope to have brought of the existence of a relatively frequent trophic proto- 

 zoan fauna in certain soils and the rough indication of some possible methods 

 of dealing with this fauna. How far this fauna under certain conditions exer- 

 cises a deleterious influence on plant growth is rather a question for the agri- 

 culturist than the zoologist. 



" The startling success in the Lee Valley of the treatment of sicli soils by 

 partial sterilization, introduced by Russell, would seem to present a very 

 strong argument in favor of the view that these protozoa do exercise an im- 

 portant influence on plant growth in these soils. We have, by means of the 

 method described above, been able to establish the occurrence of a trophic 

 protozoan fauna in certain field soils that we have examined, and to this ques- 

 tion we hope to return in a future paper." 



A bibliography of 29 references to literature on the subject is given. 



Methods in soil bacteriolog'y. — VII, Ammonification and nitrification in 

 soil and solution, F. Lohnis and H. H. Green {Centhl. Bald. [ctc.'\, 2. AM., 

 40 {1914), No. 19-21, pp. 457-479). — A continuation of previous studies of fac- 

 tors effecting ammonification and nitrification in soil and solution (E. S. R., 30, 

 p. 218) is reported. 



Aeration, the concentration of the material undergoing decomposition, and 

 more particularly, its distribution in the medium, were found to be important 

 factors for ammonification. In certain si>ecimens of blood meal there appeared 

 to be components which very seriously hindered ammonihcation in solution and 

 in saturated soil, and to a much less extent in well aerated soil or sand media. 



In solution or in sand media, higher concentrations of ammonia lowered the 

 nitrification. The alkaline reaction resulting from the use of basic magnesium 

 carbonate to cultivate the nitrite organisms hindered or suppressed the effective 

 conversion of nitrite into nitrate, as did also the adoption of a temperature of 

 from 30 to 35° C. Neutral chalk gave more satisfactory results than did mag- 

 nesium carbonate. It is pointed out that by varying the conditions in regard to 

 depth of layer analytical figures for nitrification in solution tests may be made 

 to run above, below, or parallel with those of soil tests. " The same solution, 

 if supplied with both sodium nitrate and ammonium sulphate, may give rise 

 to nitrification in shallow layer and denitrification in deep layer; if further 

 supplied with suitable organic compounds, may lead to nitrate assimilation in 

 shallow layer." 



It is concluded that no necessary fundamental difference exists between bac- 

 teriological processes in soil and solution media, and that the most important 

 factors in both are: (1) Nature and quantity of material usetl as substrata; 

 (2) concentration and distribution of the substrata in the medium; (3) aera- 

 tion; (4) diffusion, absorption, destruction, or evaporation of metabolic 

 products; (5) reaction of the medium; (6) temperature; and (7) duration of 

 the experiment. 



" The fact that in soil tests, in consequence of absori)tion, more perfect dis- 

 tribution of substrata, and superior aeration, the processes in the laboratory may 

 proceed faster than in solution, does not by any moans .justify the conclusion 

 that soil tests more closely represent field conditions." Observations conceraiug 

 the course of decomposition processes in the field are mentioned as indicating 



