THE SALMON 211 



which spread rapidly until large areas of the skin are affected. 

 They move into shallow water in such a helpless state that it 

 is easy to take them out. In 1882 the late Professor Huxley 

 contributed a paper to the Quarterly Journal of the {Micro- 

 scopical Society^ which contained practically all that is known 

 of the nature of the disease at the present day. He satisfied 

 himself and others that it was caused by the ravages of a 

 minute fungus, known as Saprolegnia ferax, the same which 

 may often be seen on the bodies of dead flies adhering to 

 the window-panes in autumn, and closely akin to Peronospora, 

 which causes the potato blight. Probably the spores can 

 only obtain a footing where the fish has received some external 

 injury, when they will fix themselves and multiply rapidly ; 

 just as bacilli invade the flesh of an apple and form brown 

 patches where the corky integument of the fruit has been 

 broken or bruised. It is highly improbable that salmon were 

 free from this affection previous to 1877, though it had 

 escaped particular attention until that year. No remedy or 

 palliative has been discovered for it. River conservators 

 generally direct their watchers to remove the dead and dying 

 fish from the water and bury them; but probably this would 

 only be of advantage if the bodies were burned, otherwise it 

 is easy to imagine many ways in which the spores of the 

 fungus will find their way back into the river. Like all 

 low vegetable organisms, the Saprolegnia manifests abnormal 

 activity and speed of reproduction at irregular periods ; 

 and when these recur, salmon are sure to suffer. Only let 

 no fishery owner listen to the groundless doctrine so often 

 advanced by local wiseacres, to the effect that the disease is 

 the result of an over-stock of salmon. In seasons when Sapro- 

 legnia is abundant, owing to meteorological or other con- 

 ditions of which we can render no account, a percentage of 

 salmon in the river will be attacked. Where there is a large 

 stock of salmon, the number of diseased fish will attract much 

 attention, and people will leap to the conclusion that the large 



