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EDINBURGH, the internal organs were perfectly healthy. They were eaten, and were quite 



good. The disease is purely, external : it is a vegetable parasite, which is 



the cause and not the effect of disease. It takes root apparently in the 

 cutaneous tissues of the fish and grows there. It is like muscardine on the 

 silkworm, and like fungoid diseases affecting the human race, or vegetable 

 fungi on trees. 



Cannot say what is the cause. Thinks a crowded state of the pools with all 

 kinds of fish would, if long continued, injure their state of health. If one or 

 two fish died it would make matters worse. 



Objects to pollution, which may, if of certain kinds, affect fish, but not, 

 if only moderate. In the Water of Leith, about one mile from Edinburgh, 

 an open town drain enters at Coatbridge, and there used to be a great collec- 

 tion of trout below it forty years ago. One was caught 8 lbs. in weight, but 

 there are none now there, the stream being now excessively polluted. All 

 animals will survive a certain amount of pollution, but will not sustain it if 

 it is concentrated. The water runs slowly. Indigo is purely vegetable ; thinks 

 it is not a poison. Snow-broth does not, bethinks, contain less oxygen than 

 rain-water. If water freezes, then oxygen is given out. Water unfrozen will 

 retain its oxygen, and the more so because it is cold. The melting of ice 

 will not affect the supply of oxygen in the water. It will readily absorb its 

 oxygen. The current of water may be stopped by ice, and the fish would then 

 be deprived of oxygen. The fish would be suffocated. The ice in ponds 

 must be broken, or the fish would be killed. At Linlithgow Loch the eels last 

 year died because the ice cut oft' the supply of oxygen. 



On general principles, the weakening of the constitution of fish would 

 predispose them to the attacks of Saprolegnia ferax. It is the feeble fish 

 that would be attacked first, as feeble men chiefly are the first attacked by 

 any epidemic. But when epidemics occur the healthy soon also suffer. 



Blood poisoning has a restricted meaning, and the overcrowding and un- 

 healthiness of fish could hardly be called blood poisoning. 



Does not know if the fungus in the Nith and Tweed is the same as that 

 observed on the kelts in former years. Evidence is required to prove this. 



Fungi cannot be distinguished without microscopic investigation. Disease 

 always exists sporadically, but certain causes must concur to render it an epidemic. 

 Thinks the same rule may hold good with regard to the Saprolegnia. Grouse 

 disease, and cattle plague, and potato disease, are analogous. 



It is a purely cutaneous disease. Thinks so because in the slighter forms 

 he has seen the fungus removed, and no sign of disease underneath except a 

 slight discoloration. 



Has frequently seen ordinary fungus on gold fishes, and also saw it on 

 minnows in a polluted null' dam at Dunfermline. Sewage was there. It 

 seemed the common confervoid fungus. 



Dead salmon should be buried, and dying fish too. 



Knows the Whitadder. Fished there from 1822 to 1832. Caught very 

 fine trout and sea trout. Examined the fish, and never saw anything like 

 disease in the spring at that time. Fished a fortnight every spring. The sea 

 trout were usually spent fish. The sea trout used to run up the river then, 

 and salmon as far as Abbey St. Bathans. 



Roods have been much affected by land drainage. From 1822 to 1832 the 

 floods made the river unfishable for three or four days, and the river kept in 

 good condition for a week afterwards for fly-fishing. The river now can be 

 fished in a day after a flood and is run too low again to be fished in a day or 

 two. Thinks this may affect the running of salmon. The draining of the 

 hills in the south of Scotland had begun before the Drainage Act of 1847. 



The fish should be distributed as much as possible, and should be passed up 

 weirs and down again easily, especially down, because it is then that the 

 disease principally appears. Apparently sea water kills the disease. Has 

 heard, on inquiry, of no case of disease in the sea fishings of the Tweed. 

 Desires to see experiments carried out as to overcrowding. This can easily be 

 done. Would also have in different rivers, both diseased and exempt from 

 disease, experienced observers to see when and where the disease begins. 



Observations on temperature should be made. 



The fishermen and others should be better instructed by competent authori- 

 ties how to examine the specimens of fish. 



