BY W. SAVILLE-KENT, F.L.S. 61 



of a caustic nature, as in tanks newly lined with Portland 

 Cement, the symptoms of the disease are greatly aggravated. 

 In all of these instances the parasitic growth is commonly 

 known as the Aquarium fungus and was formerly supposed 

 to represent a distinct species. A careful investigation has, 

 however, demonstrated it to be in all respects identical with 

 the Saprolegnia ferax of the salmon disease. I would dwell 

 longer upon this circumstance of the alkalinity of the water 

 in association with this fungus, since it has been recognised 

 by one of our highest authorities at Home as not improbably 

 furnishing the key to the origin of the disease. In the 

 course of the discussion following upon the paper on the 

 salmon disease contributed by Professor Huxley to the 

 International Fisheries Exhibition Conference, 1883, already 

 quoted, the Marquis of Exeter, who is a most enthusiastic 

 trout and salmon breeder, drew attention to the fact that 

 the water in the district of his hatcheries was very highly 

 impregnated with lime, that the fish hatched were very exten- 

 sively attacked by the fungus, and the only remedy for 

 the. fish when so attacked being a bath of salt-water. 

 In responding to this and other observations. Professor 

 Huxley remarked: — "That he had been much interested 

 in what Lord Exeter had said respecting the limy character 

 of the water of his district, because when the Fisheries 

 Exhibition was opened all the trout and other fresh water 

 fish in the new tanks, with one consent began to show 

 disease. In fact he had an opportunity of studying in the 

 Aquarium the fungus on one of these fish, and of satisfying 

 himself that it was exactly the same thing as the salmon 

 disease. That interested him very much in consequence of 

 a remark made by Mr. Saville-Kent, who had paid consider- 

 able attention to these subjects. He (Mr. Saville-Kent) had 

 said to him as they walked round the Aquarium — that the 

 disease was a matter of course, because the water had not been 

 allowed to run sufficiently long through the newly cemented 

 reservoirs and tanks, and wherever that was the case the 

 Saprolegnia was almost certain to make its appearance. That 

 opened up his mind to a very interesting chapter of inquiry. 

 It was very possible that any super-abundance of lime in the 

 caustic state might have a very considerable effect in bringing 

 about the development of the disease. In the first place, 

 fungi of all kinds were extremely sensitive to small degrees of 

 acidity and alkalinity in the water, and secondly, the condition 

 of acidity and alkalinity was extremely likely, however small 

 its extent might be, to have a very definite effect on the 

 epidermis of the fish. This, therefore, suggested a line of 

 investigation that was likely to prove extremely fruitful." 

 Subsequent to this conference, experiments were instituted 



