of Edinburgh, Session 1878-79. 
233 
fungus disease of salmon and other fish in the rivers at present 
affected by it, I think it is only necessary to relate the fact, that 
diseased fish are found in those rivers many miles above all sources 
of pollution, to prove that it cannot have originated from that cause. 
In the Eden Kiver, for twelve miles above Carlisle, a district in 
which there is no big town or other sources of pollution, the fungus 
disease has been found as deadly as below Carlisle after the sewage 
of the city has entered the river. In the Tweed also, both trout 
and greyling, which are non-migratory fish, have been found 
affected with fungus where no source of pollution is known to exist ; 
for I have obtained trout from near Broughton, and greyling from 
near Stobo, both of which are from seven to ten miles above 
Peebles, the town highest up the Tweed. Mr Buckland also, in 
his Seventeenth Beport on the Salmon Fisheries, England and 
Wales, 1878, states “that we must look to other circumstances in 
order to diagnose the origin of the mysterious disease.” 
The theory of overstocking as the cause of the disease has been 
advocated by Mr Buckland in the same report. He considers that 
“ owing to the absence of freshes (spates) in a river, the spawned 
fish do not find their way to the sea, so that they accumulate in the 
pools in which the disease breaks out amongst them, as gaol-fever 
affected the crowded prisons in former times.” 
In May 1874 the Tweed Commissioners constructed a small pond 
for experimental purposes, which measured 36 feet by 16 feet, on 
the side of a small stream called Carham Burn, from which a run of 
water was supplied to the pond by a drain pipe. On 7th May 
1874, 130 sea-trout smolts, the average length of each being 8 
inches, were taken from the Tweed and placed in this pond. After 
an interval of two years they were specially examined, weighed, 
and measured on the 25th May 1876. Seventy fish were found in 
the pond, the average length of each was 12 J inches; they were 
now in the whitling stage, and in fine condition. After another 
interval of two years there was another examination, when they 
were weighed and measured on the 23d May 1878, when sixty-six 
sea-trout, of the average length of 14f inches, were found in the 
pond. 
In the interval between the examinations, and probably in the 
season 1876-77, the fish hud spawned in the pond, and a numerous 
