184 AMID THE HIGH HILLS 
but these had no doubt been caught or died long 
before I began my experiments. I am also quite 
certain, for the reasons already mentioned, that 
they had left no descendants. Every year, in 
May or June, about 2^ acres of the loch are 
covered with a common kind of rush, the " Horse- 
tail," Equisetum maximum, and about one-quarter 
of an acre with grass, which, I believe, is a species 
of Scirpus. In the rushes and round them are 
patches of a kind of surface weed which is common 
in Highland lochs, and which, as every fly-fisher 
in the Highlands knows, is a great danger to 
him. This weed, the scientific name of which 
is, I am told, Potamogeton polygonifolius, covers 
an area of some 20 square yards. Lastly, and 
most important of all, there is in the loch a con- 
siderable quantity of the well-known Water Milfoil 
or shrimp-weed, Myriophylliivi verticiUatum, which 
in this water produced quantities of fresh-water 
shrimp. 
By August and September the rushes have, of 
course, largely increased, and extend to nearly 
four acres, leaving a comparatively small part of 
the loch which can be fished. The depth of the 
loch is about 3j feet all over with the exception 
of two places, a very small part of it, where it is 
