in the Bureau of Soils, conducted mainly with reference to the indi- 
vidual compounds actually occurring in soils, have brought to light 
much important information. Likewise the work of Jodidi, 1 Robin- 
son, 1 and others, is of interest in its bearing on the hydrolytic prod- 
ucts split off by means of acids. From the investigations on the 
hydrolytic products it has been shown that soils vary considerably 
in regard to the relative percentages of the several groups of nitrogen 
compounds split off in the treatment, and although only a compara- 
tively small number of soils have been studied, these, in the main, 
have been found to yield the greatest amount of nitrogen in the form 
of monamino acids. Approximately 25 per cent of the nitrogen 
split off was in the form of amids, while the diamino nitrogen has 
been found in still smaller amounts, usually not more than 10 per cent 
of the total nitrogen dissolved, 
It is not necessary to discuss in detail the studies previously made 
on this subject. It is sufficient to say that too much importance can 
hardly be given to the nitrogen of soils. The element lies at the very 
foundation of plant growth. The use of nitrogenous fertilizers has 
assumed enormous proportions throughout the world. In Hawaii 
extremely heavy applications have been made for many years, and 
the tendency during the past few years has been toward even greater 
applications. Many of the soils, however, contain a relatively high 
percentage of nitrogen. In some instances, even where very heavy 
applications of nitrogenous fertilizers are made, the soils contain 0.5 
per cent or more of nitrogen. 
Investigations on nitrification and ammonification in different 
Hawaiian soils have been under way in this laboratory for some time, 
and the results obtained have been of such nature as to emphasize the 
need for a better understanding of the chemical nature of the nitrogen 
bodies contained in these soils. Studies have accordingly been under- 
taken on this subject, employing the process of acid hydrolysis. In 
this work the nitrogen as a whole has been studied by subjecting to 
hydrolysis weighed portions of the original soils. On account of the 
great importance generally attached to humus, and the limited state 
of knowledge concerning the chemistry of this material, some study 
was devoted to the alkali soluble nitrogen bodies. 
Since the substances to be investigated originally came from a num- 
ber of plants, the protein of which has not been sufficiently studied, 
and have probably already undergone much change through the action 
of bacteria, there are no definitely understood materials to start with. 
The hydrolytic products obtained, therefore, leave much room for 
speculation. Just how far the cleavages had already gone in the soils 
previous to treatment remains a matter for much further work before 
definite conclusions can be drawn. 
) Loc. cit. 
