BY W. SAVILLE-KENT, F.L.S. 55 



legnia upon diseased fish, and whicla have been detached from 

 one of the salmon that recently died at the Salmon Ponds. 

 Mounted specimens, illustrating the moi-e minute structure of 

 this fungus, are exhibited in the adjacent microscopes. This 

 more minute structure as there shown, and which I have also 

 delineated on the accorapanying diagram, consists of an inter- 

 lacing network of branching threads or hyphse, commonly 

 called the " mycelium " of the fungus, and from which arise 

 erect sub-cylindrical or club-shaped seed capsules or " sporan- 

 gia." Within each such sporangium may be developed several 

 hundred microscopic seeds or zoospores, every one of which, 

 should it alight upon congenial soil, such as a sore on a fish's 

 back or any dead animal matter, is capable of developing into 

 an extensive fungus colony. Millions of these minute seeds or 

 zoospores may be developed from a single tuft of fungus not 

 more than one quarter of an inch in diameter, and as these 

 are provided with locomotive organs or cilia, wherewith they 

 can traverse the water in every direction, it may be anticipated 

 that in those waters where the fungus is abundant, a wounded 

 fish has little or no chance of escape. There is yet another 

 form of seed or spore known as the " oospore " by which this 

 fungus may be developed, but which is of much rarer occur- 

 rence and provides for the latent or resting phases of the 

 species. 



At the spawning season when the male fish fight and 

 lacerate one another, and also abrade the surfaces of their 

 bodies in excavating the nests or " redds " in which the ova 

 of the females are deposited, the fungus, Sajjrolegnia, almost 

 invariably attacks them. On some occasions it is so abun- 

 dantly developed as to constitute a veritable epidemic which 

 may be communicated to apparently healthy fish. It is more 

 than probable, however, that in such cases the tissues of the 

 fish affected are already in a diseased and impoverished 

 state, and present a suitable nidus for the establishment of 

 the fungus. As will be familiar to many present, a very 

 destructive outbreak of this fungoid disease attacked the 

 salmon in the English and Scotch rivers in the year 1878, 

 and has been more or less prevalent in later years. Thus, in 

 the annual report of the local Board of Conservators 

 of the Tweed district for the year 1881, it is recorded that no 

 less than 14,600 salmon had succumbed in that river to this 

 disease, making with the two preceding years a total of 

 over 22,000. While up to the present time nothing is known 

 absolutely or accurately concerning the immediate origin of 

 these epidemic outbreaks, there is, I think, much evidence to 

 show, in the case more especially of apparently healthy fish 

 being attacked, that the absence of sufficient oxygen in the 

 water for the healthy maintenance of the fish, either through 



