of the Fishery Board for Scotland. 



369 



the waters of the rivers examined. In the present report it has been 

 thought advisable to depart, in some measure, from the course already 

 followed, and rather to attempt an investigation of certain fungi found 

 in fish affected by disease ; to endeavour to work out their life-history 

 and inter-relationship ; and thence to utilise the knowledge gained by 

 subsequent determinate investigation of the forms found in river water 

 in various situations and at different times of the year. Bacteria are, 

 for the most part, true fungi living as parasites upon decaying vegetable 

 and animal tissues, which by their agency are decomposed and rendered 

 subservient for further use. They are further, to a certain extent, in 

 many cases interdependent upon each other j thus while certain forms 

 can exist upon a certain soil, others would find such a substratum 

 unsuitable for them, but after the former had subsisted upon it for 

 some time, they by their decomposing action might make it suitable 

 for other forms for which it previously was not so. 



As an instance of this I need only cite the well-known fact, that 

 toruhe find a condition perfectly suited to their wants in certain 

 saccharine solutions, but after a time they either, by using up the 

 materials contained in it, or by forming as a result of their decomposing 

 action certain compounds directly inimical to their own welfare, cease 

 to grow. When this has happened however, we find certain other 

 bacterial forms stepping in and flourishing luxuriantly. This is an 

 instance of a natural law, and capable of almost universal application, 

 but as yet it has only been applied to a very few series of organisms. 

 A knowledge of the manner in which it obtains in river-water fish- 

 disease must, it is evident, be of the utmost practical importance. 



It is a widely-known fact that for many years certain of our rivers 

 have been at various times infested with fish affected with salmon disease, 

 and in Professor Huxley's report for the year 1881 there is given a 

 historical account of several of our most severe epidemics, in which 

 tremendous numbers of salmon were destroyed by the fungus. 



Attention was strongly drawn to it first in the year 1877, when the 

 Esk and Nith, two rivers which flow towards the Solway Firth, were seen 

 to have diseased salmon present. Following this it passed to the Eden, 

 and in 1879 it was observed to be present in the Tweed, shortly assum- 

 ing an epidemic form, so that in 1880 a special commission was appointed 

 to investigate it. At this period it was found to have extended to the 

 Nith, Annan, Esk, Eden, Cree, and Dee, all rivers which flow into the 

 Solway Firth; to the Doon, and the Ayr in Ayrshire; the Derwent in 

 Cumberland ; and to the Lune in Lancashire. Since then outbreaks 

 have been noticed in North Wales, occurring in the Severn, the Ogwen, 

 and the Conway ; also in the Tay and North and South Esk in Scotland. 



I am informed by Sir Thomas Brady that disease has been reported as 

 existing in the upper waters of the River Slaney in Ireland, but he has 

 not himself seen distinct evidence of the disease in question. Mr Speedie 

 of Perth has written me to the effect that there is no disease in the 

 western or northern rivers of Sutherlandshire this year, while on the east 

 the Helmsdale and Brora are very bad, but that so far the average take of 

 salmon has not been affected by it. He also states that he has seen 'plenty 

 ' of diseased fish in Stockholm and also in New York,' and that he ' saw 

 ' one day in Fulton Market about fifty salmon affected with fungus in 

 ' the same manner as they are here.' In the Fifth Report of the Fishery 

 Board for Scotland, there is a report by Mr Joseph Fraser — concerning 

 the salmon disease in South Esk, in which he states that in the month of 

 August 1886 he found one dead sea-trout in the Kinnaird water, to all 

 appearance dead with the fungus. Until the September following the 



