THE LAWES AGRICULTURAL TRUST 307 



nitrogen-fixing organisms living free in the soil, and from one of the experimental 

 fields considerable light has been thrown upon the origin of the accumulated 

 nitrogen in virgin soils. The research of the late R. Warington, F.R.S., upon 

 nitrification and the organisms concerned therein was conducted in the 

 Rothamsted laboratory. Latterly the existence in the soil of another group 

 of larger organisms which reduce its fertility by keeping in check the develop- 

 ment of bacteria has been demonstrated, and this subject is now under investi- 

 gation, both in the laboratory and in the field. 



4. Miscellaneous. Other investigations have dealt with the botanical com- 

 position of the herbage of meadows and the change brought about by manurial 

 and other treatment, the nitrogen constituents of rain and drainage waters, 

 the effects of plant growth and of manures upon the acidity or alkalinity of 

 the soil, the removal of calcium carbonate from the soil, and the effects of 

 manures and soils upon the composition of farm crops. 



X. STANDARD WEIGHTS AND MEASURES. 



The Imperial Standard Yard and Pound in actual use for all important 

 comparisons are at the Standards Office. Four copies of each of them are 

 deposited in other places in case of injury or loss of the standards. One set 

 of copies is in the custody of the Royal Society. 



x 2 



