36 FISHERIES OF THE ORIENTAL REGION, 



European superintendence, would have vastly increased in value. 

 So late as the year 1857 it was not known what tissue produced 

 the isinglass, and consequently what ought to be got rid of and 

 what retained. Care should be taken that the gelatinous portion 

 is not contaminated by the blood or other tissues of the fish, other- 

 wise it acquires a bad smell, and is very difficult to purify. 



It should be remembered, therefore, that there are a few 

 tissues which form the several tunics of the air-bladder : — (1) A 

 very fine membrane, which is the epithelial layer ; (2) an 

 extremely fine internal one containing crystalline corpuscles, which 

 cause the silvery shining appearance so frequently seen ; (3) an 

 outer membrane of fibrous texture, often attaining to considerable 

 thickness. This is the portion which yields the isinglass. (4) 

 Outside this isinglass there is, in many fishes, a layer of muscles. 



When the fish from which the isinglass is taken is caught, the 

 air-bladder is cut out and thrown on one side without any care to 

 cleanse or preserve it. It is during this time that" it acquires the 

 appearance and smell that deprives it of so much of its value. 

 When Dr. Cantor first had his attention directed to the product, 

 and the demand there was for it in China, he made lengthened 

 inquiries into the best method of improving the trade. He found 

 that the fish which mainly supplied the Malayan isinglass was 

 Polynemus indicus, to which reference has already been made. 

 This is the "Suleah fish" of Bengal. It is an exceedingly coarse 

 fish, but when salted and spiced is converted into * Burtah," a 

 piquant relish highly appreciated by Anglo-Indians. 



When the air bladders of the Suleah are dry they are pellucid, 

 but so tough that they will turn the edge of a sharp knife. They 

 are tongue-shaped, and weigh about 12 ounces f?). They have 

 always attached to them many of the albuminous membranes, 

 which, if the isinglass is to be of the best quality, must be 

 removed while they are fresh. They are covered by a thin cob- 

 web of small blood-vessels, which if neglected, stains and spots 

 them with blood, and the whole becomes hard and consolidated 

 together, and putrid in places. 



