NOTES ON INOCULATION OF FISHES WITH SAPROLEGNIA FERAX. 305 



the one on the twelfth day, the other on the fifteenth day, after 

 inoculation. At the same time the experiment was extended to two 

 other healthy S. J'ario, and the only difference made was that, in 

 the latter case, the fishes were supplied with water containing about 

 half per cent, of lime-water added. Here, again, the disease 

 appeared on the third day on both fishes, but on the eighth day 

 they died, not so extensively diseased as those in ordinary water — 

 the fungus infesting them being in amount almost equal to that on 

 the fishes of the corresponding experiment after the same period of 

 time. They died soon after the beginning of what may be called 

 the time of languid movements. Before these inoculations were 

 made newly-killed flies were rubbed on the mucous coating of all 

 the fish, and these flies were then placed in cultivation by them- 

 selves, some in ordinary water and others in the water containing 

 lime from the supply-cistern. On none of these flies did Suprulcgnia 

 appear, but in a few days they were covered with a common mould 

 — just as has happened in all my attempts to obtain Suprolegnia by 

 simply placing flies in water (whether ordinary water or water con- 

 taining lime), though this method has succeeded in the hands of 

 many other observers in other places. 



" A fresh attempt was then made on March 15tli with a more 

 convenient arrangement of tanks, the subject of experiment this 

 time being young salmon hatched in the Fisheries Exhibition. 

 These fish were, or rather, I should say, are — since they are still 

 alive, except one — parr, beginning to lose their spots. They were 

 all perfectly healthy in appearance. Three of them were placed in 

 each of the four tanks — two tanks supplied with ordinary water, 

 and two with water containing lime, this time about \ per cent. 

 The three in one tank fi-om each of the pairs of tanks were 

 inoculated, the two other tanks remaining untouched as check 

 experiments (in all cases a similar arrangement has been made) ; 

 and, after a slight appearance of the fungus on inoculated fishes 

 living inider both conditions, the promise of success was not 

 fulfilled, and by March 20tli they were all apparently healthy again. 

 Similar cultivation experiments with flies rubbed as before on the 

 fish previous to inoculation were made, and again there was no 

 result. On March 20th the whole of the experiment of the 15th 

 was repeated on the same fishes. The slight appearance of the 

 disease followed as before, gradually diminishing, and has dis- 

 appeared except in three cases — two in ordinary water and one in 

 water containing lime. One of these fishes I have killed, and 

 examination shows a slight development of the fungus, more in 

 the epidermis than externally ; and the others remain, giving some 

 promise of success. A negative result was again obtained with the 

 flies rubbed before inoculation. 



" I should state that in all successful cases the disease has first 

 appeared on the region of inoculation, and from there it has spread 

 not always continuously ; sometimes an outbreak has occurred on 

 a new place, most frequently on the tail. The time from inocula- 

 tion to death corresi^onds with the periods in the cases of inoculated 

 dace. The temperature variations afl'ect the cultivations so slightly 



Journal of Botany. — Vol. 23. [Oct., 1885.] x 



