234 THE FKESH-WATEi; FISHES OF EUROPE. 



spawn firsts and the youngest last. They increase rapidly ; but tlieir lives 

 are short, since they are a principal prey of carnivorous fishes and water 

 birds, which follow their shoals. In some places they are prized as bait, but 

 are nowhere valued as food, though captured in great numbers for the bright 

 silvery pigment upon the scales. The species is found in Europe only, 

 north of the Alps. 



The fishes are frequently infested with tape-worm, which Yarrell records 

 to be often longer than the fish ; and it has been supposed that the irregular 

 swimming which has gained for some fishes the name of Mad Bleak, is due 

 to the annoyance of internal parasites. Sometimes, however, the bird which 

 feeds on the fish inherits the parasite, which makes itself at home in the new 

 abode when its former host is dissolved. 



The Chinese are said to have been the first to have discovered the art of 

 using the silvery pigment from fish scales for ornamental purposes. In the 

 sixteenth century the Venetians, who introduced the art to Europe, imitated 

 pearls so successfully with this preparation that their industry was supj)ressed 

 l)y the Government as fraiidulent. 



More than two hundred years ago the art of making artificial pearls found 

 a home in France, and has reached such perfection that its results, exhibited in 

 the International Exhibitions, almost defied detection of the manufactured 

 l)earl. Yarrell mentions that formerly a considerable trade was carried on by 

 Thames fishermen in supplying the French market with scales of the Bleak 

 for the manufacture of the " Essence d'Orient,^^ but even in his time the 

 French had learned to obtain the scales from fishes in their own rivers. In 

 England there was formerly a considerable demand for imitation pearls, which 

 about the time of the 1851 Exhibition still made a conspicuous show in shops 

 devoted to articles of personal adornment. Small glass beads were lined with 

 pigment, and then filled with wax. The cheapest sorts were prepared from the 

 scales of the Roach and Dace, were dull in lustre, and rather yellow. A better 

 kind of pearl was made from the Bleak, but the scales of the Whitebait were 

 most valued, and sold at a price varying from one guinea to five guineas a 

 pound. At the present day, according to Blanchard, the scales of the Bleak 

 sell at from twenty to twenty-four francs a kilogramme, and 8,000 fishes are 

 necessary to provide this quantity. From this one-quarter of the weight of 

 the "Essence d'Orient^'' is obtained. 



The method of preparation of this substance is to scrape off the abdominal 

 scales with a knife. The scales are washed and triturated, so as to separate 

 the pigment, which has a metallic aspect, and falls to the bottom of the vessel 

 in microscopic particles. This sediment is then washed with ammonia, to 

 remove the organic matter. Seen under the microscope, the mass which then 



