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 
