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of Edinburgh, Session 1878 - 79 . 
that recovered the head was more or less tohite, and continued so 
for years afterwards ; and even to this day, every now and then, a 
white head, as the gillies called the diseased fish, comes up from 
the sea. 
“ It is a curious and interesting fact that the condition of the fish 
was not affected in even the far advanced cases. Nutrition did not 
appear to have been interfered with. The body was as plump and 
fat and the pink colour as high as usual. I did not eat of those 
very far gone in the disease ; of those less so I did eat, and found 
their flavour as in the healthy salmon. You will observe from 
what I have said that our disease, whatever might have been its 
cause, was a disease of the head, and confined to the head. 
“ So much for the form of our disease * now as to its origin. 
Whatever may have been the predisposing or its immediate cause, 
it is certain that the fish brought it with them from the sea, or, as 
in my opinion, acquired it in the tide-way in Loch Roch-Roag. 
They did not take it down with them when they went to the sea as 
kelts or smolts, but they brought it up from the sea in summer as 
grilse and fresh-run salmon. After mature consideration of all the 
attendant circumstances, I have come to the conclusion that the 
disease arose from the fish being kept moving so long up and down 
between the salt and brackish waters. With each flood tide they 
moved up in dense masses toward the mouth of the river, vainly 
looking for water sufficient to carry them into it, and, when the 
ebb came, going down again for two or three miles into the deep 
and comparatively salter water. This continuing for weeks, with 
the water in the bay becoming daily more shallow, the heat and 
bright sun during the day was sufficient, in my opinion, to account 
for the disease. I have already said the sea trout did not suffer, 
because very little water was sufficient to take them into the river, 
and they were kept outside for but a short time. Again, the fish 
in the Blackwater, a river within two miles of the Grimasto, had 
no disease — at least, I did not hear of any having been seen in it ; 
the reason, as I think, being that at all times, except in the lowest 
neaps, the tide came up so near its mouth as to allow the fish to get 
into its lowest pools without much difficulty. Against my theory 
there is this to be said : as already mentioned, the island of Lewis 
has been subject within the last fifteen years, to my knowledge, to 
2 F 
VOL. x. 
