1904 - 5 .] 
Flora of Scottish Lakes. 
969' 
carbonate, a phenomenon unknown in the Ness area (fig. 3, 
p. 1021). As may he inferred from the foregoing remarks, the flora 
of the Lismore lakes differs considerably from that of the lakes in 
the Loch Ness area. 
3. The Lakes near Nairn. — These differ in many respects from 
those of the two areas already described. The lakes in the two 
foregoing areas mostly owe their existence to the action of glaciers, 
are frequently situated in deep valleys overshadowed by hills, or 
in excavations upon the mountains themselves, rock and precipice 
being a characteristic feature of their rugged and frequently tree- 
less shores, while considerable and often great depth is a marked 
feature. Here, however, we have extensive sheets of water 
existing in mere depressions among former sand-hills of the sea- 
shore. Their shores are flat, muddy, and, but for the artificial 
forest about them, featureless (fig. 103). Where vegetation is 
abundant the mud is deep, and evil-smelling when disturbed. In 
the two former areas described a continuous flat and muddy shore 
has not occurred, neither has the mud often been of the stinking 
kind. In the deeper lakes of the two former areas a large portion 
of the bottom is destitute of flora. The scattered organic detritus 
is therefore much less than in these shallow lakes which have 
abundant vegetation all over the bottom. The refuse-eating fauna, 
existing at the bottom, are consequently, in the former case, able 
to maintain an equilibrium between supply and demand ; and 
the lake bottom consists essentially of the non-fetid excrement of 
these creatures. Here, however, we have lakes whose floor is 
wholly carpeted with vegetation, and the supply of organic 
detritus is greatly in excess of the demand of any refuse-eating 
organisms that may exist, and therefore fetid mud results from 
the processes of unhindered decomposition. In these lakes we 
find but little evidence of lime, and little or no acid peat extract. 
The water is somewhat stagnant, and, from the considerable 
amount of decomposing organic matter, it presents a turbid and 
unwholesome appearance. In these respects this district again 
differs from those of the two former areas considered. In conse- 
quence of the depressed situation, and with surrounding forest, 
these lakes are much sheltered from wind. Although in close 
proximity to the sea, the water is not brackish. A certain 
