NOTES ON INOCULATION OF FISHES WITH SAPROLEGNIA FERAX. 303 



(February 19th), by rubbing the top of the fish's head with a fly on 

 which the fungus was growing. In the case of one Sahno ferox a 

 very shght abrasion of the epidermis over the region referred to had 

 been previously made by gently rubbing it with fine sand. 



" Again no result followed these experiments, and on March 2nd 

 they were repeated on the same two dace, this time by rubbing 

 (without previous abrasion) the left side of the fish midway between 

 the gills and the tail-fin. The change in the region rubbed was 

 made in consequence of the observation that on nearly all the 

 diseased dace I had seen the part named was commonly the first 

 affected, the right side equally with left. On March 5th each of 

 these fish had a small tuft of what was afterwards found to be 

 SaproU'i/nid fera.v growing on the region of inoculation, and by 

 March lOtli it had grown to a large patch. On this day one of the 

 fisii escaped from the water, and when found was lying dead close 

 to the vessel in which it had been confined. It then bore a similar 

 appearance to the other, as regards the progress of the disease. 

 The other died on March 16th, its body being nearly covered with 

 a luxuriant growth of Saprolenniaferax, the oospores of which were 

 present, but sparingly. 



" Of the eight unsuccessful experiments half had been made 

 before the appearance, and half in the presence, of oospores. 

 Since, however, none had been successfully made in the absence of 

 oospores, I determined to enquire if that affected the possibility of 

 infection. Two healthy dace were therefore rubbed, on March 26th, 

 over the same region as in the successful cases, with Saprolegnia 

 ferax, on which neither oogonium nor oospore could be found, the 

 zoosporangia being plentiful, however, and numerously ripe. In 

 both cases the experiment was successful, and indeed the activity 

 of the disease appeared to be greater from the fact that one fish 

 succumbed in ten days and the other in fourteen. 



" In the case of the fish which died on the tenth day the body 

 was nearly covered with the fungus, but in the case of the other 

 which died on the fourteenth day the disease was confined to one 

 side, extending from the mouth over the gills down to the tail-fin, 

 both sides of which, however, were badly affected. 



" On both fishes, contrary to my expectation, oospores were 

 more numerous than on those individuals which had been inoculated 

 with oospore-bearing material." 



II. 



" In continuation of the inoculation experiments with Sapro- 

 ler/nid fenix made last year on the dace, I have begun a fresh series 

 this time on fishes belonging to the Salnionidcc, and the results are 

 briefly as follows: — 



"The agent used in all the inoculations was Saprolet/niti fcrax, 

 directly continued by cultivation from the fungus obtained by Prof. 

 Huxley in December, 1881, from a diseased Conway salmon. These 

 cultivations have been maintained since then on the fly, and 

 observed almost daily. The fungus of this stock, if it may be so 

 termed, was used last year in the inoculation experiments on the 



