1904 - 5 .] 
Flora of Scottish Lakes. 
987 
plant was obtained from this deep water. This was quite in 
accordance with expectation, seeing that the photic zone in Loch 
Ness does not extend beyond a depth of 30 feet, owing to the 
amount of matter held in solution by the water. From even the 
deepest parts of the loch there was found an appreciable quantity 
of vegetable remains, but entirely that of the terrestrial or aquatic 
flora washed out from the shore ; or of aquatic forms not found 
living in abundance in the loch, but brought into it by rivers and 
burns. It was possible to identify branches, twigs, leaves, fruits, 
■etc., of Scots Pine, Birch, Alder, Ash, Oak, Beech, Willow, Bog- 
Myrtle, Equisetum, Carex, Sphagnum, etc., all undergoing a 
process of disintegration by carbonisation. 
On 13th September, after heavy rains had caused the rivers to 
be in considerable flood, I found the surface of Loch Ness below 
Beinn a Bhacaidh covered for the distance of about a mile with 
the fruits of Betula glutinosa, Fries ., — distinguished from the 
fruit of its congener, Betula verrucosa, Fhrh., by the persistent 
stigmas exceeding the wings. These were probably brought into 
the loch by the river Tarff and the Allt Doe, and borne thence 
by westerly winds. This example serves to show how quantities 
•qf material foreign to the loch find an ultimate resting-place on 
its bottom. It also exhibits an interesting method of plant 
distribution : such prodigal scattering perhaps occurs annually. 
The sudden rise and fall of the water of Loch Ness must be 
mentioned as probably a further factor antagonistic to the well- 
being of plants. The records kept by the canal authorities at 
Fort- Augustus give the maximum of 7 feet 4 inches from the lowest 
in dry periods to the highest in wet weather. A rise of 2 feet within 
a few hours is quite a usual occurrence. At Loch Garth there is 
a rise and fall of 22 feet, caused by artificial agency ; its effect upon 
vegetation is there very evident (p. 1015). 
The following extracts from my field note-book will afford 
evidence regarding the photic zone of Loch Ness : — 
“Dredged the bottom from the point beyond the railway pier 
south of Cherry Island to the estuary of the river Oich in from 
30 feet to 50 feet of water. A great number of hauls were taken, 
but I obtained not a single evidence of any living plant being at 
the bottom.” 
