120 College of Forestry 
are generally familiar. You will have read of the “ keep- 
ing” qualities of bog water. Bodies of large animals are, 
from time to time, found buried in peat bogs. When the 
peat of these bogs is scattered on a field it becomes further 
decomposed, the nitrogen especially becomes available for 
living plants in the form of nitrates. When bog soils rise 
above the water table, the peat undergoes at least partial 
decomposition, the complete stage of which would be the 
formation of leaf mold. This stage is reached in a moist 
but well-drained high forest. It is not complete in swamp 
soils and marshes. Even in Montezuma marshes there 
appear to be basins or pockets where fibrous peat rather 
than the blacker, finer grained muck occurs. Decomposition 
is hindered in some places of the marsh more than in others. 
The extreme case of retarded decomposition exists where 
plant (and animal) remains lie indefinitely preserved — the 
scfter parts being disintegrated (macerated) but not chem- 
ically broken down in the sense that the elements which 
entered into the building up of the plant are set free in com- 
binations available for use again. 
To have in mind the essentials of what is involved here, 
recall that the active agents in this reduction or decomposi- 
tion of dead organisms (animals as well as plants) are 
certain kinds of bacteria. Whatever would retard or pre- 
vent the activity of these bacteria would retard or prevent 
the decomposition of dead organisms. Oxygen is neces- 
sary for these bacteria. A: water-soaked soil, being poorly 
aerated, reduces the oxygen supply, checks the activity of 
such bacteria and retards decomposition or results in only 
partial decomposition —e. g. muck. This is the condition 
prevailing in swamps generally. ‘Still less perfect aeration 
further impedes bacterial activity and consequently decom- 
position. This appears to be the condition which prevails 
where the tendency is toward bog development in small 
basins (kettle holes); in an arm of a lake cut off from free 
water movement (Devil’s Dye-tub at Tully Lake); im the 
middle of a swamp; in glacially blocked valleys where basins 
