30n NOTES ON INOCULATION OP FISHES WITH SAPROLEGNIA FERAX. 



(except, of course, extreme beat and cold) that I am not at present 

 disposed to attach much value to their influence in cases of in- 

 oculation, and certainly nothing has yet been observed of any value 

 in this direction. The water containing lime was prepared in a 

 cistern from which a supply-pipe led to two tanks bifurcating, and 

 thus serving each from the same source. 



" These experiments at least furnish starting-points for fresh 

 experiments, from which it is to be hoped some light may be 

 obtained as to the influence of the presence of lime." 



III. 



' ' During the latter part ot spring and the early summer of last 

 year a considerable number of the fish inhabiting the tanks in the 

 Fish Culture Museum suffered from the attacks of Saprole<jnia. 

 The young salmon, which had been hatched in the Fisheries 

 Exhibition and reared in the Fish Culture Museum, sufl^ered most, 

 and nearly all of those attacked died. This outbreak was entirely 

 unexpected, and, considering the circumstances under which it 

 took place, its origin was at first inexplicable. The water in which 

 the fish in question were living came from the same source as that 

 which had a great number of times undergone the test of immersing 

 flies in it without these showing a sign of the growth of Sapro- 

 legnia. I applied this test again to water taken before it entered 

 the tanks, and the supply remained as pure as before ; while, as 

 would be expected, water from the tanks themselves yielded Sapro- 

 legnia readily. It was thus made certain that the disease was not 

 conveyed to the fish through the water supply, and the next 

 direction enquiry took was to ascertain if by any means the disease 

 had been communicated to these fish from those in adjoining tanks, 

 which were the subject of inoculation experiment. Careful enquiry 

 brought no result. The experiments were being conducted in an 

 isolated manner, and the landing-nets, &c., used in the capture and 

 handling of diseased fish had never been employed in other tanks. 

 In my difficulties Prof. Huxley, foreseeing that the result of such 

 an enquiry could not fail to be instructive, encouraged me to 

 prosecute it, and suggested that the food given to the fish might 

 be the vehicle of the infectious material. A consideration of this 

 enabled us to pitch upon the earthworms used for this purpose as 

 most likely to yield result. Several of these were intercepted 

 while being conveyed to the tanks for food, and were placed under 

 cultivation. After the lapse of two days the Sajyrolegnia un- 

 mistakably showed itself, and, though comparison satisfied me of 

 the identity of this fungus with that of the disease, the matter was 

 put to absolute proof by using this fungus as the agent of inocula- 

 tion in the final successful experiment recorded last year. Exami- 

 nation disclosed the presence (in two cases) of oospores in the 

 earthy contents of the worms, and these, I believe, were the 

 oospores of Saprolcgnia. I never succeeded in finding any worm at 

 large on which the Saprolcgnia was growing, and, though the 

 ground was damp, I was sufficiently surprised to find alive even 

 the resting- state of this purely aquatic fungus, since desiccation at 



