Unlike that of the cod, the flesh of the herring is very rich in oil and fat. The body flesh of the herring consists essentially of two well-developed layers of adipose tissue, alternating with two layers of muscular tissue. The fat in this adipose tissue is very liquid and oily, and tends to make the fish tender. The actual amount of body fat varies widely throughout the year. It gradually rises to a maximum before spawning takes place, and diminishes slightly before spawning and afterwards rapidly to a minimum. Thus, the fat content of Manx summer herrings is about 2 per cent during the winter, and rises rapidly in June and July, until in August, just before spawning, it is over 30 per cent. The herring has a small liver which also contains some oil. Fishing is carried out with drifters. Practically all drifters to-day are steam-driven, although recently a number of motor-driven drifters have come into use. Motor-driven drifters are mostly sailing boats converted. Each drifter carries a crew of seven men, including the skipper and engineer. The boats are largely privately owned and the crew work on a share basis. A number of boats are owned by companies. The boats from the various fishing ports work round the coast, following the fishing from port to port. At Yarmouth during the fishery season there are about 1,200 drifters from nearly all the fishing ports round the coast. Stornoway, Wick, Fraserburgh, Peterhead, Aberdeen, Berwick, Whitby, and Yarmouth are all well represented. Each boat carries from 70 to 80 nets. The nets are approximately 1 in. mesh. Each net is essentially a long rectangular curtain, hanging vertically in the water. Its upper edge, which is about 55 yds. long, is buoyed up by about 80 to 84 corks distributed equidistantly along it from end to end. The net is about 6 yds. wide. Each net hangs with its upper edge about 2 fathoms below the surface of the water, being attached at each corner to two pellets or bladders, resembling large footballs, and serving as floats. Fishing nets and sails are often coated with warm gelatine, and then immersed in a strong solution of tannin. This renders the gelatine insoluble and preserves the nets against the attacks of destructive organisms. [Illustration: FIG. 12 HERRING DRIFTER] When fishing, the boat takes up a position stern on to the tide. The nets are paid out over the bow and connected up in line, and carried by the tide till they form one long line, one end of which is attached to the drifter. The position of the nets is indicated by the line of bladder floats.