MARCH 55 



the conclusion that this fungus was ' the sole cause of the 

 disease, whatever circumstances may, in a secondary 

 manner, assist its operations ' ; and this was confirmed by 

 the experiments of Mr. G. Murray, who succeeded in 

 transplanting the fungus to the bodies of dead flies, and 

 thence inoculating healthy fish, which died in consequence 

 of salmon disease. The chain of evidence seemed com- 

 plete : Saprolegnia was pronounced to be the direct agent 

 in salmon disease, and efforts to mitigate or avert the 

 latter must be directed to extirpating the fungus, and, as 

 far as possible, excluding it from our rivers. 



It has been reserved for Mr. J. Hume Patterson, 

 assistant bacteriologist to the Corporation of Glasgow, to 

 disclose the real nature of this destructive pest. Puzzled 

 to understand how Saprolegnia, which normally thrives 

 upon dead animal tissue, should find a congenial soil in 

 the living flesh of one of the most vigorous of fishes, 

 Mr. Patterson prepared cultures from the diseased parts 

 of salmon, in which was revealed the presence of a micro- 

 organism previously unrecognised, and totally distinct 

 from the Saprolegnia. By a series of scrupulously care- 

 ful experiments, which are fully explained and illustrated 

 with photographs in a Blue-book just published by the 

 Fishery Board for Scotland ' The Cause of the Salmon 

 Disease ; by J. Hume Patterson. (H.M. Stationery Office) 

 Mr. Patterson proved that this bacillus, which he has 

 named Bacillus Salmonis Pestis, is constantly present in 

 diseased fish, that it obtains access to the tissues through 

 wounds or abrasion of the skin, multiplies with exceeding 

 rapidity, and by causing necrosis or death of the muscular 

 tissue, forms a suitable nidus for the growth of Saprolegnia, 

 the spores of which abound in ordinary river water, ready to 



