FOREST, FISH AND GAME COMMISSIONER. 



225 



is easily carried to an injurious extent if one introduces fish which have 

 injuries of the skin and scales. 



The course of the disease is generally rather slow, lasting often three to 

 four weeks before the scale pouches are distributed over the entire body, 

 when the fully paralyzed fish survives only one day more. In most cases 

 the infected fish go to the bottom during the disease, and only in rare cases 

 will their transfer to clear flowing water heal them. 



In order to prevent the scale disease it is necessary to guard carefully 

 against all injuries to the skin and keep the fish in inclosures and ponds 

 which have been most thoroughly purified. Diseased fish must be sepa- 

 rated from the sound ones, and inclosures and ponds must be disinfected 

 with quicklime. 



The Red Plague of the Eel 

 (Hojer, Handbuch dcr Fischkrankheiten, pp. 15-19.) 



EEL 



An epidemic disease, sometimes of enormous extent, which may be 

 called the Red Plague on account of the characteristic red spots present on 

 the skin, occurs in the eel from time to time in different localities. This is 

 especially observed in the Danish part of the Baltic nearly to Ruegen as well 

 as in the rich eel breeding waters of the Commachio Valley, in Italy, and 

 particularly during warm summers. 



The epidemic has been well known in Commachio for some time. It 

 was reported in 17 18 by Gian Francesco Bonaveri; later by Spallanzani, 

 who stated that during thirty-eight days from July 15, 1790, 79,200 pounds 



