78 
Journal of Agricultural Research 
Vol. XXIX, No. 2 
tween the botanical composition of the 
layer of peat and its relative stage of 
decay. If this conclusion is further 
substantiated, the quantitative esti¬ 
mation of the nitrogen-free extract 
in different layers of peat materials 
should be of special significance and 
value. The quantity of this fraction 
of organic material must influence the 
character of cultural operations and 
the rate of growth of crops in the peat- 
soil horizons through which roots can 
penetrate. It is quite reasonable to 
assume that the nonnitrogenous com¬ 
ponents in the separate layers or 
horizons in peat deposits may be 
responsible for the differences in the 
water-holding capacity of peat ma¬ 
terials and in the absorption power 
for certain mineral salts and fertilizers. 
Changes of this kind may likewise con¬ 
tribute to layers with varying salinity, 
and to the stratification of acid and 
alkaline reaction in certain peat-land 
profiles. The horizons and pockets of 
well-preserved shells of mollusks ( 9, 
Pl. 1, 4) in submersed fibrous and sedi¬ 
mentary types of peat, reacting acid to 
litmus, appear to indicate that the 
organic acids present are only slightly 
soluble in water and act upon calcareous 
materials with great difficulty. 
Undoubtedly a more detailed exam¬ 
ination of peat layers in regard to their 
nitrogen-free extract would shed much 
light upon their microbiological char¬ 
acter and upon the biochemical changes 
going on during the humification of 
peat materials. Under natural condi¬ 
tions of high-water level, that is, when 
reduction prevails, the solubility of the 
substances grouped into this fraction 
is apparent in the color imparted to the 
streams which emerge from marshes, 
bogs, and swamp forests. The con¬ 
tent of water-soluble organic matter 
varies probably with the pedomorphic 
structure of the peat deposit and with 
the relative capacity for chemical alter¬ 
ations of the several layers of peat. 
The color of the solution obtained from 
freshly dug peat samples varies with 
different stages of decomposition, rang¬ 
ing from a light straw-yellow to a deep 
brown. Freezing and heating or steam¬ 
ing different peat materials are accom¬ 
panied by marked changes in the con¬ 
tent of dispersoid and colloid organic 
material. Studies are reported by 
Ostwald (86) and by Melin and Od6n 
(80), which indicate the possibility of 
using a colorimetric method for investi¬ 
gations of this kind. 
Frequently organic substances in 
peat, forming suspensions and colloidal 
solutions with water, have a strongly 
acid reaction and absorb oxygen from 
the air. Little is known as to their 
direct effects on plants, although by 
former investigations (7) it was showi* 
that such aqueous peat extracts majr 
contain organic substances of harmful 
character. A tendency was observed 
to inhibit or retard and dwarf the 
growth of higher plants as well as of 
aerobic microorganisms. The question 
is still an open one, however, whether 
some of the organic substances can be 
absorbed by plants and can be used as 
sources of carbon. 
The dilute alkali extract of peat 
materials and of the organic matter in 
mineral soils has been the object of 
numerous studies on organic decom¬ 
position. It is not the purpose of the 
present paper to review or to discuss 
the voluminous literature dealing with 
this phase of the problem. The results 
of investigations on humus, humic 
acids, on theories of adsorption and re¬ 
lated phenomena have been compre¬ 
hensively reviewed by Lohnis (26), 
Ehrenberg (11), Hoering (19), and 
more recently by Od6n (85 ). But with 
reference to the several kinds of peat 
and the marked stratigraphic differ¬ 
ences in peat deposits, the situation 
remains problematical. Neither the* 
relation of microorganisms to the forma¬ 
tion of muck and humus is understood, 
nor is the chemical composition of the 
organic compounds in the nitrogen-free 
extract of specific types of muck and 
peat a well-known subject. It should 
be highly instructive to determine 
whether the increase in nitrogen-free 
extract is due largely to the decom¬ 
position of cellulose and lignin com¬ 
plexes or to that of other plant prod¬ 
ucts. Attempts should be made there¬ 
fore leading to a more detailed analysis 
and to the isolation of compounds from 
the nitrogen-free extract. Indeed the 
change toward the formation of such 
substances is so marked that a com¬ 
parative cellulose and lignin determina¬ 
tion of various peat materials under¬ 
going decay might well serve to throw 
further light upon the problem of 
humus. 
THE ETHER EXTRACT IN DIFFER¬ 
ENT PEAT MATERIALS 
Ether-alcohol extract of peat mate¬ 
rials contains dissolved waxes, variable 
mixtures of gummy resins, balsams, ter- 
penes, and similar substances together 
with other complex constituents- 
They are storage, waste, and residual 
products of very variable chemical 
structure, and most of them were origi¬ 
nally secreted by cells and glands of 
different kinds of plants. A study of 
solvents for the separation of these sub¬ 
stances from peat materials with par- 
