230 REPORT OF THE COMMISSIONER OF FISH AND FISHERIES. 
fragments in the fresh state, fibers are seen, which, in places, have pre- 
served their normal aspect and their striation, and at other points more 
or less considerable spaces, where the muscular substance is filled with 
a vitreous refringent mass, around and in the intervals of which lie 
fatty droplets, yellowish granules, and spores. The degeneration invades 
gradually the muscular substance of the primitive fibers, and one finds 
it in parts of these elements, where the parasite appears not to have 
penetrated. On the contrary, the neighboring, noninfested, primitive 
fibers seem exempt from that alteration, and one frequently observes a 
degenerated fiber surrounded by healthy ones. 
The fiber thus degenerated and broken up, is soon invaded by pha- 
gocytal cells coming, some from the sarcolemma, others from the con- 
nective tissue. This latter, at the diseased points, is the seat of avery 
marked irritative proliferation. 
It is necessary to distinguish, in the degenerated fiber, the parts 
where spores are found in great number, and those where these elements 
are few or absent, the degenerative process in the latter case having 
originated from the presence of the parasite at a different point. 
In this latter case the cells which have penetrated into the degen- 
erated tissue multiply rapidly; in proportion as their number augments, 
one sees the muscular débris diminish; very soon they have completely 
disappeared, the place of the fiber being finally occupied by connective 
tissue. While these phenomena occur, the irritation is propagated, the 
connective-tissue proliferation extends itself, and a sclerosis of the 
neighboring muscle region, with atrophy of the primitive fibers, is pro- 
duced. 
At the points where the degenerated fiber incloses a great number 
of spores, the formation of connective tissue is at first limited to a 
thickening of the perimysium. There are thus formed connective-tissue 
bridges, separating the spaces occupied by the spores, and which 
correspond to disappeared primitive fibers. These facts are seen 
especially clearly on transverse sections. Little by little these bridges 
increase in thickness, at the same time their tissue becomes more dense; 
they thus form around each space a fibrous shell, which tends to con- 
tract more and more. There seems to be here a true encystment of 
the parasite, such as is produced around foreign bodies introduced into 
the tissues. 
Symptoms.—Barbels attacked are less lively than usual and have 
much difficulty in ascending streams; surface of body, dull, grayish 
yellow, oily, slippery (Meuse; Railliet). 
Less lively than usual, easily caught in the hand, breasting the ecur- 
rent with difficulty, avoiding rapid water (their usual haunt), taken in 
great numbers in bow-nets. Some affirm, others deny, that the sick 
fish will not bite at the hook. Diseased fish are of all sizes. Those 
seriously affected are of a weight much below that indicated by their 
external appearance, the body being in fact more or less dilated. On 
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