SAPROLEGNIA FERAX, SALMON DISEASE. 155 



out among cattle the whole herd are slaughtered? 

 indiscriminately ; if one were suffered to live, disease 

 would certainly break out among the next lot it 

 came in contact with, and as saprolegnia is an 

 infectious or contagious disease, why should not the 

 same principle be applied to fish ? But it would be 

 impossible to destroy every salmon affected with 

 disease in any river, and therefore to endeavour to 

 stamp it out by such means, although helping to 

 lessen the chances of infecting healthy fish, must 

 end, as it has ended, in failure. 



The only available cure at present known for 

 salmon disease is salt water, as diseased fish which 

 are fortunate enough to reach the sea, apparently 

 get cured, but it is not certain that the cure is 

 complete. 



Salt water destroys the fungus adhering to the 

 fish, and the sore created thereby may heal over ; 

 still, in many cases, the disease may lie dormant in 

 the system of the fish, to break out again under 

 conditions favourable to its development. This 



