THE MYXOSPORIDIA, OR PSOROSPERMS OF FISHES. 231 



this account the fisbermeii often estimate the wei.ulit at nearly double 

 the actual (Eailliet.) 



According to Vet. Surg'. Hanzo, the affected fishes float on the siu-face 

 as though poisoned with Goecuhis indious. 



Epidemics. — In the Meuse it has manifested itself with the characters 

 of a veritable epidemic during three consecutive years, from 1883 to 

 1885, inclusive. It became progressively more aggravated, reaching 

 its maximum of intensity towards the middle of 1SS5. On certain days 

 of that year M. Ladague had interred nearly 100 kilograms of barbels ; 

 the Meuse was covered with dead fish. The disease subsided little by 

 little, and actually appeared to become extinct, but it could almost be 

 said that the combat closed for want of combatants. 



In the district of Ardennes it was remarked only in the Meuse itself; 

 all the affluents have always been spared. The maximum intensity, 

 according to Railliet, was reached about the middle of 1881. On certain 

 days, at Mezieres alone, as many as 100 kilos (about 200 pounds) were 

 interred. Some years later the disease had disappeared from that 

 region, but raged down stream at Montherme and Givet. 



In the neighborhood of ISTancy the barbels die in great numbers 

 (Megnin). 



In the Aisne Ivailliet was informed of ravages of the disease occur- 

 ring near Eethel. The disease, he thinks, extended to the Aisne a,ud 

 the Marne from the Moselle via the canals. 



In the Marne a considerable number of barbels floated dead or unable 

 to escape, down the lower Marne. The disease appears to have begun 

 (at least in the neighborhood of Charenton) about June 15; thence it 

 progressively increased, attaining its maximum at the time of emptying 

 of the St. Maurice Canal. It persisted till the end of July, at which 

 date Eailliet's information ceased. 



In the Seine it did not extend above the Port a 1' Anglais dam. The 

 Grenelle fishermen, Railliet was informed, had seen a great number of 

 sick barbels. The Seine thus ai3pears invaded, without doubt consecu- 

 tively, fi'om the Marne. 



In the Rhine and its tributaries, the Saar and Mosel, according to 

 Ludwig, it seems to have appeared at least several decades ago without, 

 however, ever having attained the magnitude that it has reached in 

 l^te years in the Mosel. Tlie disease has there been observed since the 

 end of 1870 and has so increased that, especially in the warm summer 

 months, the dying and dead fish from the upper Mosel and Saar pass 

 Trier by the hundreds, and at Zell (on the Mosel) it is reported that they 

 spread a carrion-like odor. According to Pfeiffer, in the Saar and Mosel 

 during the summer of 1890 no very extensive mortality occurred. 



Contributory causes. — As regards age as a predisposing factor, Railliet 

 observes that in the Meuse the young barbels are attacked as well as 

 the old, the weights of dead fish varying from 22 grams to 6 or 7 

 kilograms. 



