e( Warm sluggish water, shallow pools, badly aerated reservoirs 

 f? or tanks, containing much nitrogeneous substance, make a 

 Sl fitting breeding-place for this disease. Fish are more subject to 

 " it at certain seasons of the year than at others ; salmon at the 

 (e end of the spawning season are especially subject to its attack, 

 " and a great mortality prevails among them. Mr. Livingston 

 te Stone, in his report of the salmon-hatching establishment on the 

 (( McCloud river, says : ' A marked change takes place in the 

 " salmon a little before the middle of August. The males grow 

 " deep and thin, and the dog-teeth begin to show themselves. 

 " The females are now big with spawn. They become foul and 

 e: diseased, and very much emaciated. Blotches of fungus appear 

 " on their heads and bodies, and in various places are long white 

 " patches, where the skin is partly worn, off. Their fins and tails 

 te become badly mutilated, and in a short time they die exhausted. 

 " By the 1st of October most of the fish that were in the river in 

 ? August are dead.' " Mr Moore adds, " The fact remains that 

 ft ninety-nine hundredths, if not all, of the salmon in the upper 

 " tributaries of the Sacramento river appear to die immediately 

 " after their first spawning." 



From these various opinions, as well as from those expressed 

 in other able papers printed, in the Appendix,* we infer that the 

 disease which we have been appointed to investigate is a fungus 

 known to naturalists as the Saprolegnia ferax, which multiplies 

 both a-sexually and bi-sexually with extraordinary rapidity. We 

 have now to consider (1) whether this fungus has recently been 

 introduced into this country, or (2) whether it has existed for any 

 lengthened period and has been only recently stimulated into 

 unusual reproductive energy. 



The scientific evidence chiefly points to the latter of these con- 

 clusions. The sporules of the Saprolegnia ferax are said to be 

 commonly present in running water ; and assuming, as we are 

 bound to assume, that facts stated with such confidence and on 

 such high authority are correct, we conclude that the Saprolegnia 

 is no new disease, but that it has existed in what may be called 

 a sporadic form for a long series of years. The practical 

 evidence to a certain extent corroborates this conclusion. 

 Fishermen of many years' experience told us on the Tweed, 

 the Lune, and elsewhere that fish with fungus upon them had 

 been constantly taken in past years. We do not, indeed, attach 

 much importance to this evidence, because the very interesting 

 account, which we print in the Appendix,f from the Honorary 

 Consulting Naturalist of Southport Aquarium, seems to show that 

 there are two distinct fungi by which fish are attacked which 

 may easily be mistaken by non-scientific observers. The same 

 thing was clearly stated to us by Mr. Stirling. It is possible that 

 some of the fish, affected with fungus in previous years, may have 

 been attacked by another fungus than the Saprolegnia. But 



* Appendix II., p. 103. 

 f Appendix II., p. 109. 



