80 The Fungus of Salmon Disease. 



able to it. The method it has of taking up its nourishment 

 through its roots is essentially different to that of the ordinary- 

 organisms of decomposition, which, moving freely in a liquid, 

 assimilate through their pores. A possible stimulus, therefore, 

 given by food in solution, is for this reason doubtful, and even 

 if the fungus could take it up, I hold that it is quite unneces- 

 sary. 



The disease cannot originate in salt water — there can be no 

 doubt of that — as not only are freshly-run fish always clean, but 

 no reliable instance of the disease occurring in salt water is on 

 record. Experiments of my own, in mixtures of salt water 

 varying from full strength to high dilution, have been quite 

 negative in the strong salt solutions, and though a mixture of 

 one salt water in six of fresh will allow the fungus to grow, its 

 spore formation is faulty, and development not normally healthy. 

 In a salt-water solution of io°/ strength, growth was not 

 unfavourable, and plentiful sporulation resulted. 



To apply a remedy to the running waters of a river would be 

 an ungrateful task, if not an impossible one. The spores of the 

 fungus have all the appearance of being able to resist conditions 

 that would kill any fish ; but if a fish is removed without 

 injury from a river, the fungus can be killed with a sprinkle of 

 alum or borax, or even common salt, and I am told of the 

 favourable use of a weak permigranate solution, but this re- 

 quires to be skilfully and quickly done, and the fish must then 

 be put in an enclosure and watched, and the remedy again applied 

 if necessary. Such treatment is, I believe, not uncommon in 

 fish-culture establishments, where the disease is frequently met 

 with, and fish of all kinds are often cured. Remedial measures 

 ought rather be searched for among possible changes that may 

 have crept in during long periods of years to influence the 

 vitality of the fish themselves. The fungus is having the best 

 of the unnatural struggle just now, and will continue to do so 

 as long as it is favoured by such chances. A sickly fish, or one 

 wanting in its power to resist fungoid attack, could not be re- 

 cognised by its eating qualities, and the conditions of unfavour- 

 able influence on salmon, though in themselves unchanged for 



