G. GENERAL NATURAL HISTORY AND ZOOLOGY. 209 



the mouths of the bays, but more sparingly in the bays them- 

 selves and in the open sea, diminishing in amount, apparently, 

 with the depth. At certain periods of summer, however, it 

 appears in such- immense abundance that the sea is colored 

 red by it. When floating in this way upon the surface it at- 

 tracts innumerable schools of mackerel as well as of herring, 

 which are then much less shy than usual, and the scene is 

 one of impressive activity, owing to the number of boats and 

 nets employed in fishing. On a careful examination, this sub- 

 stance was found to consist almost entirely of small copepod 

 crustaceans, the largest scarcely the thirtieth of an inch in 

 length, and barely distinguishable by the naked eye. They 

 were mostly species of Calanus, Eikocalanus^ Centropages, 

 and Anomalocera. 



It can hardly be believed that such minute and almost mi- 

 croscopic animals can be of so much importance to the wel- 

 fare of a nation ; but, in reality, the mackerel andthe autum- 

 nal herring owe their fatness to them, the microscope reveal- 

 ing through their thin shells the fat lying in distinct strips 

 between the muscles and intestines. 



These same crustaceans occur also off Spitzbergen in such 

 abundance as to furnish food to innumerable water-fowl, and 

 even the whales feed upon them to a great extent. If, now, 

 the herring has taken in a large quantity of this red food, and 

 is then captured and killed without its having been fully di- 

 gested, the animal matter in the stomach of the fish begins 

 to spoil before it can be reached by the salt, and the stomach 

 thus becomes putrid, as well as the large blood-vessel which 

 lies under the back, the coloring matter imparting a reddish 

 tinge to the flesh along the backbone. For this reason it is 

 required by law to keep herring three days in the nets in 

 water, that all the contents of the stomach may be complete- 

 ly digested, while the fish is prevented from taking in a fresh 

 supply. Sometimes, however, the winds drift this herring- 

 food into the nets, and furnish to the herring an opportunity 

 which they eagerly embrace, rendering them again liable to 

 the difficulty just "mentioned. 



When a herring, on being squeezed, discharges a yellow 

 pulp, this is known as " yellow meat," or gulaat. This is not 

 so abundant as the other, but appears, like the " red meat," 

 to be composed in part of transparent copepods, together 



