106 



THE AMEKICAN MONTHLY 



[June, 



of the South of Scotland ; the use 

 of artificial manures, washed by the 

 heavy rains and melting snows of 

 the past Winter, and the existence 

 in the streams of various polluting 

 matters from factories and towns, 

 are very likely to have combined 

 to produce the conditions favorable 

 to the present outbreak." 



Again salmon in rivers are sub- 

 ject to artificial conditions and can- 

 not follow their natural instincts. 

 In evidence of this assertion Mr. 

 F. Buckland writes : " A large 

 number of fish which have done 

 spawning are moved by their in- 

 stinct to get down as quickly as 

 possible to the sea ; but they can- 

 not do so on account of their jour- 

 ney being delayed by the weirs 

 and 'caulds' on the Tweed and 

 her tributaries. The instinct of the 

 invalid salmon teaches them to go 

 to the sea, because it is certain the 

 fungus cannot exist in the sea, and 

 secondly, because they wish to pick 

 up condition and fatten upon their 

 natural food, which consists of 

 sand-eels, sprats, lierring, smelts, 

 and the fry of other sea-fish. When 

 these fish are delayed above the 

 weirs the crowding tends to disse- 

 minate the disease, for I am sure 

 the fungus is ' catching.' 



"Whatever, therefore, may be the 

 cause of the disease, the fact stares 

 us in the face that crowding above 

 the weirs most certainly tends to 

 foster and spread its ravages, just 

 as when pilgrims at Mecca become 

 too crowded, the plague is started 

 and spread." 



Mr. Buckland here asserts posi- 

 tively " that it is certain the fungus 

 cannot exist in the sea ; " its deve- 

 lopment may be checked, but it is 

 questionable if the vitality of the 

 resting spores would be impaired 

 by continual immersion in sea 

 water. The salmon's recovery may 

 also be due to improved feeding. 



and hence tone and increased vital- 

 ity, which enables the fish to resist 

 the encroachment, and ultimately 

 rid itself of the parasite. I once 

 tried a little experiment with 

 sticklebacks ; of these I had a dozen 

 or so, all more or less affected with 

 the fungoid growth. I transferred 

 them from a fresh-water aquarium 

 to sea-water (sticklebacks live well 

 in sea-water after they become ac- 

 customed to its density) ; but al- 

 though their existence may have been 

 somewhat prolonged, the fungus 

 ultimately reached their gills and 

 killed them all. 



The excessive protection afforded 

 to many species of game, and un- 

 mitigated destruction of so-called 

 vermin, which naturally clear off 

 the sickly and weak, appears to in- 

 duce many hitherto unknown ma- 

 ladies among them. Such diseases 

 do not confine their ravages to the 

 point of origin ; usually contagious, 

 they extend their limits and in- 

 clude both strong and weak in a 

 common destruction. 



So with salmon, it may be that 

 in artificial fish-hatching and rear- 

 ing a large percentage of weakly 

 fish reach maturity, which, in an or- 

 dinary way, would have succumbed 

 to their natural enemies ; such 

 would be the first seized by the 

 fungoid parasite in question, and 

 of necessity convey the contagion 

 to others. An outbreak so exces- 

 sive can only be ascribed to some 

 general cause, as it is scarcely rea- 

 sonable to suppose that the conta- 

 minated rivers became polluted all 

 at once. Where the disease appears, 

 each infected fish becomes an agent 

 of destruction to its kind, and an 

 assiduous emissary in disseminating 

 myriads of motile and resting 

 spores, all seeking or waiting for 

 the conditions essential to develop- 

 ment. 



The question of chief interest to 



