532 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



one patch of fuugus upon it, which was seated within its mouth on the 

 inner margin of the right lower jaw ; it filled the mouth, which was dis- 

 tended by its growth ; and every other part of its body was free from 

 fungus or blemish of any kind. 



The reason why most of the fish affected with fungus are first attacked 

 by it upon their heads may arise from various causes. All river fish 

 present their heads to the downward current of the water, whether they 

 are swimming or at rest, and as the spores of the fungus are floating 

 down with the stream the heads of the fish are the first parts to come 

 in contact with and be affected by them. Further, the mucous glands 

 are most numerous and active upon the head of the fish, which is also 

 more thickly covered with mucous than other pans of the body, and the 

 spores which fall upon it adhere more readily ; and the fins and tail, 

 from their continuous waving motion, are more liable to arrest the pass- 

 ing spores than the parts of the body from which they spring, and, from 

 this cause, are generally affected sooner than th ? bodies of the fish. 



The number of the dead and dying fish of all kinds removed from the 

 river Eden in 1878 by the police, and published by Mr. Buckland in his 

 report for that year, show that there were 1,271 salmon, 140 fresh-water 

 trout, and 40 brandlings or parr, being over 50 of the large fish to every 

 one of the smaller. About 1,000 of the salmon were clean fish, and it 

 may be inferred that the trout and parr were also clean, which goes far 

 to show that the so-called disease is as much a mechanical as a func- 

 tional one. Further, from documents descriptive of the effects of the 

 disease in the river Tweed, in the lower district, during this season, 

 1879, which were collected by the police from taxmen and practical fish- 

 ermen on the river, I find that the proportion of large fish affected, dead, 

 or dying — namely, salmon and sea-trout — is very great compared with 

 the smaller fish which were found to be affected in a similar way. The 

 smaller fish alluded to consist of river-trout, grayling, smolts, perch, and 

 gray mullet. 



From observations of the fuugus, and of the fish affected by it, I am 

 led to believe that the so-called salmon disease does not depend upon a 

 prediseased condition of |he fish. It is a true parasitic attack, to which 

 every fish in any affected river seems to be liable, as every kind of fish, 

 irrespective of condition, appears to be a proper nidus for the propaga- 

 tion of the Sajprolegnia ferax when a living spore from that fungus at- 

 taches itself to it. While engaged during the spring and summer in 

 the microscopic examination of the SaproJegnia ferax^ I observed that as 

 the season advanced many of the patches of fungus seated upon the 

 fish were barren, consisting of spear-shaped filaments only, having no 

 zoosporaugia at their apex, and consequently they produced no zoo- 

 spores. The filaments were long and very thin, and almost void of pro- 

 toplasmic contents, indicating that the plant was losing its force and in 

 a state of decay. 



The 8aprolegnia feraXj in all probabilitv, is always present in our rivers 



