Vll 



" It had a soft fungus on the gills. The gills were covered with 

 " a slimy matter ; the fish might have died of suffocation." 



We might easily multiply similar descriptive extracts from the 

 evidence which is printed in theAppendix* 



The fungus adhering to various parts of the body being at all 

 events the outward and visible sign of the salmon disease,, whether 

 it really be so from a scientific point of view or not, we shall now 

 examine the evidence : first, as to the nature of the fungus ; and 

 secondly, as to the way in which it affects the fish. 



Fungi chiefly grow on dead and decaying substances, and may 

 be called the scavengers of nature. They help to dissolve and 

 remove the exuvias of one generation, and convert it into vegetable 

 mould. 



Good examples of terrestrial forms of parasitic fungi are the 

 dry-rot fungus, so fatal to timber under certain circumstances ; 

 puff-balls ; and several fungi, sometimes of bright colours, that are 

 found among the decaying branches and leaves in damp woods. 

 In wine cellars, also, vegetable fungi are common, especially 

 a fungus which attacks and completely destroys the bark of a 

 tree which we know under the form of cork. 



"We also find fungoid disease in the following cases: — 

 Smut of wheat. 

 Potato fungus. 

 Grape fungus. 

 Coffee leaf disease. 

 Blue mould of cheese. 



Fungi, however, also attack animals. The silkworm, for instance, 

 is liable to a disease known as muscardine. The fungus in this case 

 resembles common mould, and rapidly spreads. Fungus on fish is 

 not uncommon. Fungi on fish have been observed in America, 

 China, France, Germany, and other countries. The particular 

 fungus which is observed on fish affected with the " salmon 

 " disease" is known as the Saprolegnia ferax. 



In the opinion of. Sir Robert Christison " it takes root appa- 

 " rently in the cutaneous tissues of the fish and grows there. It 

 u is like muscardine on the silkworm, and like fungoid diseases 

 " affecting the human race, or vegetable funoi on trees." 



Sir E. Christison thinks it is "a purely cutaneous disease, 

 e \ because in the slighter forms he has seen the fungus removed 

 " and no sign of disease underneath except a slight discoloration." 



Mr. Erasmus Wilson, to whom some specimens of diseased 

 salmon were submitted by Mr. Bucklancl, is of a similar opinion. 

 " The appearance of the disease," he writes, " very closely resem- 

 " bles ringworm in the human subject, in which also there is a 

 " fungiform growth, and I have no hesitation in referring the 

 " cutaneous disease of the salmon to a similar cause. The parts most 

 " affected were those most distant from the centre of circulation, 

 tl namely, the fins and tail, and of these the whole surface was coated 



* A plate showing the appearance of the Saprolegnia ferax under the microscope, 

 ■which we owe to the courtesy of the Editor of the " Gardener's Chronicle," in which 

 the drawing originally appeared, is published on the opposite page. 



