260 THE ZOOLOGIST. 
a splendid male, which our former keeper shot from the nest, he having 
also shot at the female—Crirron (Cobham Hall, Kent). 
‘Tue Satmon Dissase.—At a meeting of the Dumfriesshire Natural 
History Society, held on the 30th April last, the Secretary read a paper on 
the origin of the Salmon disease. Upon examination and careful dissection 
of specimens under the microscope, he found that when Salmon are first 
affected they have one or two small white spots generally near or on one of 
the fins, often the dorsal or caudal fin. These spots gradually extend, until 
in many cases the fish is nearly covered. When the disease begins to affect 
the constitution of the fish, they look languid, and gradually draw into the 
smooth and shallow water. When seen in the river the white spots look 
like mould, such as is generally seen on decaying animal or vegetable 
matter. When the fish is taken out of the water that mouldiness assumes 
a matted, slimy appearance, and can easily be scraped from the scales with 
a sharp knife, in most cases leaving no trace. The mouldy-looking substance 
placed under the microscope reveals that it is a fungus—viz , Saprolegnia 
ferax, the filaments of which take all sorts of forms. The spores of the 
fungus have a motion of their own inside the parent cell, and when the 
proper time comes they are discharged by the sporangia at the apex of the 
filaments, and then take the form of zoospores, having two “ cilia” moving 
about in the water like true animalcula, ready to attach themselves to any 
proper substance that may come in their way on which to germinate, and 
throw out filaments similar to those from which they came. Considering the 
thousands of filaments on one single spot of the disease, and the number of 
spores given off by each, the quantity of zoospores lodged in and floated down 
an affected river must be beyond calculation. One feature noticed in con- 
nection with these zoospores was, that if a stream of liquid was made to flow 
across the field they could attach themselves to the glass, so that they were 
not carried away by the stream, and by the same means, therefore, they 
could attach themselves to stones, &c., in the river, or to the dorsal fin of a 
Salmon. ‘The roots of the fungus were not traced beyond the skin that covers 
the scales. On making a cut into the fish through the fungus, there is seen 
an inflamed, unhealthy-looking stratum of muscle below the skin, of varying 
thickness. In one fish examined it extended right through to the inside. 
Sections of this muscle when placed under the microscope were found to be 
literally one mass of life—that life being a species of bacteria, or small 
discoid-looking bodies, embedded in and moving amongst the striated muscle 
fibre of the fish; and when, by pressure or otherwise, they are forced into 
the surrounding fluid they have a power of motion in a circular direction. 
In some fish examined the muscle was almost detached from the strong 
fibro-muscle layer of the skin, and the muscle fibres of that layer were not 
