1904 - 5 .] Flora of Scottish Lakes. 999 
waves having power over practically the whole of the loch ; this 
is more especially the case if the shores happen to be of gravel. 
Loch Lochy is not properly in the Ness area, as it drains into 
Loch Linnhe. Some dredging by the Mermaid , at depths to 
500 feet, furnished exactly similar results to those already 
described for Loch Ness. Beyond this I have only examined the 
north-east end of the loch, which is practically the same in 
character and flora as Loch Oich ; the water, however, is less peaty. 
The mountains are here faced with glacial gravel, through which 
the numerous water - courses have carved enormous gullies, 
bringing down the gravel into the loch (fig. 42). By this action, 
two burns upon opposite shores have brought into the loch at 
Kilfinnan almost enough material to divide the loch into twain 
(fig. 42). 
We now proceed to smaller lochs of a more or less elevated 
position, situated on the mountains north-west of Lochs Lochy, 
Oich, and Ness. Some botanists have endeavoured in the past to 
distinguish mountain lochs by the presence of certain plants, as, 
for example, Isoetes lacustris, Lobelia Dortmanna, Potamogeton 
polygonifolius, Sparganium natans, S. minimum, and by the 
absence of reeds at the margin. This may undoubtedly be the 
case in some districts, but in the Loch Ness area the presence or 
absence of such plants and associations are certainly no criteria of 
the elevation of a loch. All the plants enumerated are to be 
found at so low a level as Loch Ness (52 feet above sea) ; and a 
reedy margin is found at quite highland situations, as will be 
shown later; whilst it is almost absent in such low-lying lochs 
as Oich and Ness. The reason is not one altogether of elevation 
for the presence or absence of certain associations of plants, but 
is rather due to the supply of food-salts, and the amount of 
exposure of the water to winds, coupled with the nature of the 
shore. The mountain lakes usually drain a very small area, poor 
in food-salts and rich in acid humus ; consequently only those 
plants are found in them that can obtain their requirements from 
an apparently scanty food supply, combined with the presence 
of humic acids. Such plants are those that have been associated 
with mountain lakes. Lowland lakes usually drain a wider area, 
and soils poor in peat and rich in food-salts; which, although 
