REVIEWS 119 



supply of nitrogen. In meadows covered with shrubs and in spruce 

 forests where the ground cover is herbaceous, the nitrogen of the humus 

 is changed into nitrates, though the ground cover does not usually con- 

 tain an accumulation of nitrogen. Plant colonies on bare mineral soils 

 are often made up of nitrophilous plants, which store up nitrates in their 

 tissues. In coniferous forests where the ground cover is composed of 

 lichens and mosses, the nitrogen is not converted into nitrates, but the 

 decay of litter terminates with the formation of ammonia and ammo- 

 nium compounds. 



Earths in the process of nitrification often have an acid reaction. 

 Such earths often can convert ammonium sulphate into nitrates only 

 very slowly, and denitrifying agents are usually quite generally dis- 

 tributed through them. Natural earths in the process of nitrification 

 can by storing form just as large or larger amounts of nitrates as com- 

 mon agricultural soil. 



Nitrification is influenced to a marked degree by the earth-forming 

 processes, as well as by the climate. As the extent of nitrification has 

 a strong influence upon the composition of plant colonies on a soil, the 

 earth-forming factors will in many cases have a decisive influence upon 

 their composition. Lime in the soil, as well as ground water containing 

 dissolved calcium carbonate, assists nitrification. Similar forest trees 

 grow more rapidly on soils where the nitrogen is converted into nitrates 

 than where it is not. By proper forest management it should be pos- 

 sible to handle many forests in such a manner that nitrates will be 

 formed in the soil, resulting in a decided increase in the amount of 

 timber produced ; but even on soils where nitrates are not formed ex- 

 cellent yields of pine and spruce can be obtained. In the latter case the 

 rate of growth seems to be quite proportional to the rapidity with which 

 ammonia is formed in the soil, and even here the soil-forming processes 

 can be accelerated by proper forest management. 



B. L. G. 



Commission of Consenvtion of Canada. Report of the Eighth An- 

 nual Meeting, held at Ottawa, Ontario, January 16 and 17, ic)!;. 



This contains reports of the committees on Forests, Lands, Minerals, 

 Public Health, Waters and Water Powers, and Fisheries, Ciainc aiicl 

 Fur-bearing Animals. In addition, there are a number of addresses, 

 delivered at the animal meeting, dealing with dinVreiit aspects of the 

 conservation situation in Canada. The annual address of the chairman. 

 Sir Clifford Sifton, gives an admirable general survey of the whole 



