272 BULLETIN OF THE BUSSEY INSTITUTION. 
large, although not determined; the peculiar odor of these products - 
while burning being very appreciable.” , 
In all probability a good part if not the whole of the nitrogenous 
matters of these exceedingly fertile soils are very unlike those con- 
tained in ordinary peat or in moor-earth; but the variations in the 
quality of vegetable mould from different sources must generally be 
regarded rather as differences of degree than as actual distinctions in 
kind. Here in New England, many kinds of peat which are thought 
to do little or no good as manure, when applied directly to the land, 
produce distinctly useful effects after they have been mellowed by 
exposure to the weather. It is known that the quality of the nitro- 
genized constituents of vegetable mould depends largely upon the 
climate of the region in which the mould has formed. In high 
northern latitudes, and even in some less inclement regions, where the 
climate, though equable, and not excessively cold, is very moist, the 
decay of vegetable matters commonly produces moor-earth; while as 
the result of such decay in more temperate climates, like our own, we - 
find peat of various degrees of consistency, including the matters that 
are commonly called “muck” in this vicinity. But in the tropics, peat 
is rarely if ever seen, except upon high mountains, though matters akin 
to leaf-mould are there abundant. In direct parallelism with these well- 
known geological facts, it would appear that the employment of active 
nitrogenous manures is more necessary for the successful cultivation 
of land in cold countries than in countries that are warm or hot. 
On the one hand, the luxuriant growth of vegetation in a tropical 
swamp shows that woody plants can there obtain from the soil, with 
the utmost ease, all the nitrogen they need; while, upon the other, 
the good results that have been so constantly obtained by the use of 
nitrate of soda and of ammonia salts in the farming practice of 
England, Scotland, and Germany, illustrate the need there is in those 
climates of providing for certain crops an artificial supply of active 
nitrogen. But while it has been clearly proved for Northern Europe, 
that the natural supplies of nitrogen are altogether inadequate for the 
growth of maximum crops of grain, even upon soils that are highly 
charged with humus, very little is known as to the extent of country 
to which this dogma is applicable. There is still much to be learned 
with regard to the geographical and isothermal limits within which the 
use of artificial nitrogenous manures will be found to be necessary or 
