Dr MacCuUocli on Peat 
47 
It is unnecessary to add to this enumeration the Sphagnum pa- 
lustre, and some other plants which were before mentioned un- 
der the head of marsh-peat. 
The next division is that of ForesUpeat It has often been 
asserted, that all peat was the produce of decayed woods ; but 
the preceding remarks render it unnecessary to enter into a for- 
mal discussion on the unfounded nature of that opinion. Even 
those peat-bogs which now cover the decayed trunks and roots 
of trees, and which have been supposed to have originated in 
their destruction, owe great part of their bulk to the growth 
and decay of plants subsequent to the period of their fall, and 
are now increasing by a continuation of that process which 
forms the peat of marshy or of wet moor land. During the 
growth of a forest, in favourable situations, a stratum of peat is 
formed by the accumulation of decaying leaves and branches, 
and by the death and renovation of the plants which grow under 
their shade. Where, in the lapse of time, the trees of these forests 
have fallen, whether from the effects of age, from storms, or from 
other causes, a certain portion of the wood decays, and adds to 
the original deposit ; while the growth of additional plants of 
different kinds, perpetuates the process. In these cases, the 
smaller branches, and even the larger, being exposed for a long- 
er period to the effects of air and water united, and being, from 
their size, more susceptible of decomposition, are ultimately 
converted into peat ; while, in a few situations, even the trunks 
disappear. Where, on the contrary, the growth of the peat 
stratum has been so rapid as to cover the trunks, so as to ex- 
clude the alternate action of air and water, these remain for a 
long period unchanged, and are often dug up unaltered, so as 
even to be applicable to the ordinary purposes of timber. Oak, 
in. such circumstances, is well known to acquire a black colour, 
and to become valuable for the purposes of the cabinet-maker. 
As the roots are soonest and most effectually protected from the 
causes of decay, they are generally found unchanged, even when 
the trunks have entirely mouldered away. It has been sup- 
posed that peat possessed some mysterious antiseptic properties, 
by which this effect was produced ; but it differs in no respect 
from that which equally occurs where wood is so far buried, as 
in the case of piles, as to be excluded from the influence of the 
air, or from alternations of dryness and moisture. 
