LOACHES. Ill 



the manufacture of artificial pearls. The process by which this 

 glittering material is refined and utilised is said to have originated 

 with the Chinese ; the industry has been established in France for 

 more than two hundred years. The most silvery scales are picked 

 out and scraped, and the iridescent pigment allowed to collect at 

 the bottom of the water as a sediment. This is placed in liquid 

 ammonia and sold as "essence d'orient." Small glass bulbs are 

 coated on the inner surface with this substance, and the interior 

 filled with a hard wax. The outer surface of the glass is some- 

 times dulled with hydrofluoric acid to increase the illusion, and, 

 perfectly spherical pearls being very scarce, the manufacturers of 

 these imitation pearls even go to the length of blowing the bulbs 

 irregular and lop-sided. Most of the "essence d'orient" is made 

 from the scales of the Bleak, but that obtained from Whitebait is 

 of superior quality and greater brilliance. 



In the Loaches there are from three to six pairs of barbels Loach, 

 around the mouth ; the pharyngeal teeth are in one row and in 

 moderate number. The anterior part of the air-bladder is divided 

 into a right and left chamber and enclosed in a bony capsule. 

 The Loaches have a low, elongate body, with or without minute 

 scales. They are distributed over Europe, Asia, Abyssinia, &c. 

 They are fishes of small size, living in small streams and ponds 

 and avoiding large rivers. 



In consequence of the close connection that exists between the 

 skin and the air-bladder, and between the air-bladder and the ear, 

 the fishes are very sensitive to changes in temperature and pres- 

 sure, and are known in parts of Germany as " Wetterfisch " or 

 Weather-Fishes. The commonest European Loaches are the Stone 

 Loach, Nemachilus barbatulus, 353 ; the Spined Loach, Cobitis 

 taenia, 355 • and the Pond Loach, Misgumu% fossilis, 354, the 

 largest of the three, growing to about 10 or 11 inches. 



The Spined Loach, which is scarce in Britain, may be distin- 

 guished from the other two by the presence of a small, erectile, 

 bifid spine below the eye. The Pond Loach has 10 or 12 barbels, 

 four of which are on the lower jaw ; the Stone Loach has 

 6 barbels, none of which are on the mandible, The Pond Loach 

 occurs in stagnant waters of eastern and southern Germany and 



