10 SCIENCE BULLETIN, No. 9. 



sand in both cases was supplied with the necessary mineral fertilising con- 

 stituents, but with no nitrogen. Both plants grew vigorously, the oats 

 obtaining their supply of nitrogen by the diffusion of soluble nitrogenous 

 material from the outer pot in which the legumes were growing. 



If, instead of a porous inner pot, the oats were grown in glazed pots and 

 were thus unaffected by the nitrates formed by the legumes, they produced 

 a much diminished yield, and showed the growth and colour associated with 

 lack of nitrogen. 



Another case in which a beneficial action is exerted on the growth of 

 plants by organic soil-constituents, and one in which such action cannot be 

 attributed to any direct fertilising power, is furnished by creatinine and 

 creatine. Creatinine is an organic substance which exists not only in the 

 humus of soil, but in farmyard and organic manures, and in many plants and 

 seeds, and whose presence in the soil has be3n found to indicate fertility. 



The United States Soil-Bureau * have isolated and experimented with this 

 substance, and with creatine, of which latter it is the anhydride. These 

 authors have found it in stable manure and peas used as green manures ; also 

 in wheat, S33dling wheat grain, bran, rye, some leguminous plants, and 

 potato? s. 



Both creatine and creatinine are nitrogenous substance*, and experiments 

 in manuring show that they can replace nitra'e in its tiTects en plant-growth, 

 at all events in culture solutions. 



Micro-organisms Toxic and beneficial. 



In yet another direction a great deal of interesting work lias been done, 

 showing the part played by minute organisms in relation to soil fertility. It 

 had been known for some time that treatment of the soil both by heat and 

 by antiseptics favoured the growth of crops. 



S. U. Pickering f found that when soils were either heated or treated 

 with antiseptics the total soluble organic matter of the soil was increased, 

 and at the same time toxic conditions were produced which hindered 

 germination, such inhibitory action being, however, only temporary, as the 

 toxins were subsequently destroyed, presumably by oxidation. 



.E. J. Russell and II. B. Hutchinson, J in an elaborate and careful series 

 of experiments, appear to have shown conclusively that the beneficial effect 

 of partial sterilisation by heat or antiseptics upon the growth of the 

 crop, is attributable to the larger proportion of ammonia present in the soil 

 after such treatment. These authors explain this phenomenon as follows : 

 Probably in all soils certain larger unicellular organisms (protozoa) are 

 present, which feed on the bacteria concerned in the formation of soluble 

 nitrogen compounds and keep them in check. If the soil is partially sterilised 

 by heating for a short time to the temperature of boiling water, or by 

 subjecting it to the action of vapours such as chloroform, bisulphide of 



* Schreiner, Shrrey, Sullivan, and Skinner, Bull. 83, Bureau of Soils, U.S.A. 

 + Journ. Agric. Science, vol . 3, pp. 32 and 258 . 

 $Journ. Agric. Science, vol. 3, p. 111. 



