AQUATIC I'ROJDUCTS IN ARTS AND INDUSTRIES. 219 



certain percentage oC 1 he li\ crs are diseased. This (;<mditioii is usually 

 evidenced by a greenish color or by the presence of colored spots, 

 which increase in size and number as the disease advances until the 

 entire organ is affected. Diseased livers are never used in the prepara- 

 tion of medicinal oil, but are freely utilized in making curriers' oil. 

 The size of the livers varies considerably, but averages about 12 inches 

 in length and 2^ inches in thickness in the center, the weight being 

 somewhat over half a pound. Some livers weigh onlj^ 1| ounces each, 

 and an instance is recorded by Dr. F. P. Moller of one taken in the 

 Lofoden fishery which weighed 11 pounds, its length being 4.3 inches 

 and its greatest thickness Q^ inches. 



Considerable difference exists in the size, shape, and general 

 appearance of livers of the cod family. Cod livers are elongated, 

 with the large end near the dorsal fins and the small end toward the 

 tail. Haddock livers are much shorter than those of cod, and have 

 little frills or scalloi)s on the edges, whereas those of cod are smooth. 

 Haddock and pollock livers are of a cream color, similar to those of 

 cod, while cusk and hake livers are of a light straw color. The livers 

 of all Gadidce are usually mixed together bj^ the fishermen, but in the 

 season when any particular species is abundant the livers of that 

 variety are kept separate. On the New England coast of the United 

 States cod livers predominate during the coldest months and pollock 

 are taken mostly in October and November. 



In the United States fisheries livers represent about '6^ per cent of the 

 weight of the fish, and they yield about 40 per cent of their weight in 

 oil; consequently 100,000 pounds of fish yield about 180 gallons of oil. 

 On an average, from January to June, 1,000 pounds, dressed weight, 

 of cod yield about 1 bucket, or 2| gallons, of livers, and during the 

 latter half of the year the yield increases to 4 gallons per 1,000 pounds 

 of dressed fish. A bucket of these livers yields 5 or 6 quarts of oil on 

 an average throughout the year, except that in the spring the product 

 is sometimes reduced to about 3 quarts to the bucket of livers. 

 The yield of hake livers per 1,000 pounds of fish is somewhat larger 

 than in case of cod, but the quantity of oil secured from a bucket of 

 livers is about the same. Haddock jield best from October to Decem- 

 ber, and during the spring and summer the result is small, sometimes 

 not over 1^ quarts to the bucket. On account of the small yield and 

 the conditions surrounding the haddock fishery, only about 15 per cent 

 of the livers of that species are saved in the New England fisheries^ 

 At present pollock do not yield so much as cod, av^eraging about 5 

 quarts to the bucket of livers throughout the j^ear; but previous to 

 ten years ago on the New England coast they usually yielded 7 quarts 

 of oil in the fall. 



In the Lofoden fishery, according to the official returns, ordinarily 

 20 to 30 livers are required to produce 1 gallon of medicinal oil. Dur- 

 ing some seasons the livers are quite fat, and 8 to 12 are sufficient; 



