119 



observed occurs oftener in the large fish than in the small. The second, and ™ PT1 ?J|JL, A n 

 probably a slower way, is when the fungus grows over and closes up the oper- ightham. 



cular openings of the gills, which seems to be the way those specimens have 



been suffocated, being shrouded while alive in fatal fungus, they have died in 

 their beauty, with their silvery skins unbroken. 



There is one fact connected with the Ightham epidemic, namely, that the 

 large pike, perch, and eels were not affected by the fungus disease. I am 

 unable to account for this immunity on physiological principles, and refer it to 

 the hypothesis of the " struggle for existence and survival of the fittest." It 

 would be difficult to find anywhere a purer collection of water than the 

 Ightham ponds. The main stream, upper pond, and stews, being virgin 

 spring water, uncontaminated with any pollution, so that I am convinced that 

 S. ferax can and does exist where no source of pollution is present, and 

 exercises its destructive influence upon the fish, as is evidenced by the 

 numerous deaths in the epidemic of 187-1 in the Ightham upper pond. Up to 

 the present time it has generally been held that fungus epidemic, or, as it has 

 been called, salmon disease, was confined to and had its origin in rivers fre- 

 quented by the migratory Salmonidce. At an early stage of the inquiry, 

 Sir Robert Christison referred to this, and urged that if possible it should be 

 ascertained whether the disease had ever been observed in the head waters of 

 any salmon river above any impassable obstruction, either natural or artificial. 

 The epidemic at Ightham moat and ponds answers the question Sir Robert 

 desired to be cleared up, and proves that S. ferax is not confined to rivers 

 frequented by salmon. 



In a former paper, I stated that the so-called salmon disease did not depend 

 upon a pre-existing functional disorder in the fish. I am still of this opinion, 

 and point to the fish from Ightham as a further proof that this is the case. 

 I also stated my belief that S. ferax existed at all times and probably in all 

 waters, and that the presence of fish and S. ferax in the same water "under 

 certain climatic or other at present unknown influence, seems all that is 

 necessary to originate fungus epidemic. 



The epidemic at Ightham in my opinion does away with the theories o£ 

 overcrowding, including overstocking. Overcrowding of salmon in a pool in 

 a river is not analogous to overcrowding of people in a room or in a prison cell, 

 where only a certain amount of air can circulate. Salmon crowded in a pool 

 in a river, through which a stream of water flows freely, are in a condition 

 similar to a herd of cattle crowded in a pen or fold, in the open air on a hill- 

 side, where pure air is inexhaustible. In like manner, salmon crowded in a 

 pool are provided with a continuous supply of oxygen by the constant flow of 

 the river through the pool. 



As to overstocking, my own opinion as an angler of 50 years' experience, 

 and as a net fisher for a fifth of that time, is that I never found the fish too 

 plentiful anywhere ; and I do not think there ever can be too many, especially 

 trout, grilse, and salmon, in any of our rivers. Very curiously, those who 

 advocated the theory of overstocking as the cause of the fungus disease are in 

 many instances the very persons who grumble at the scarcity of the fish in 

 question, and propose to increase their number by killing them for eight or ten 

 days longer at the latter end of the season, when the fish best adapted for 

 breeding are-entering the rivers. Regarding the food supply in overstocking, 

 I quote the following statement cited by Sir Samuel Wilson of Ercildoune, 

 Australia, in his work on the acclimatisation of Californian salmon. " It is 

 " stated by Mr. Vincent Cooke of the Oregon Packing Company, that out of 

 " 98,000 salmon caught in the Columbia river in 1874, three only were found 

 " with some trace of food in their stomachs, and those seemed to have quitted 

 '*" the salt water very recently." 



The fact that the house drains into the moat might be urged by some as an 

 argument that the water there is rendered foul by the house sewage, and that 

 the pollution of the water may have had some influence in developing the 

 disease. In reply to this it must be stated that as Dr. Church points out, a 

 large body of water flows through the moat hourly, and so far from ordinary 

 house drainage being prejudicial to fish, where the water is frequently changed, 

 the finest fish as the pike, perch, and eel, are to be caught in the neighbour- 

 hood of the house drains. But if it were proved that the house drainage 

 mingling with the water of the moat served as an exciting cause for the 



