their night's work from signs which would escape the 

 ordinary looker-on, many of these points are beyond their 

 power to elucidate. A skilled fisherman will tell by the 

 colour of the water, by the flight of a flock of sea-gulls, or 

 by the movements of a school of porpoises, whether a shoal 

 of herrings, pilchards or mackerel is within " measurable 

 distance " of being caught. He will know too well, when 

 the waves are crested with that beautiful phosphorescent 

 light which visitors to the seaside like to watch on a dark 

 night, that his chances of a good catch are very small, since 

 the fish will see his nets as they hang, like a sheet of liquid 

 fire, near the surface. But he cannot tell what part the 

 minute organisms, which give rise to these phenomena, may 

 be playing in the economy of the fish ; he cannot always 

 tell you where or when the different kinds of fish spawn ; 

 he can only guess where the migratory fish go after their 

 periodical visits to the shore ; and he is utterly at a loss to 

 explain the reasons of their occasional total disappearance 

 for several years at a time from a coast which they have 

 visited regularly, year after year, as long as he can 

 recollect. Round our own coasts, off those of Norway, 

 Holland, or France, in the United States, wherever you go, 

 you will find records of the occasional utter annihilation of 

 a fishery which for years had been an annual source of 

 enormous wealth. Many thriving cities, revelling in the 

 wealth of an abundant herring fishery, for instance, have 

 been suddenly ruined because the fish have, for some 

 inscrutable reason, forsaken their accustomed haunts. The 

 history of the ancient cities of Marstrand and Uddevalla 

 in Norway, and in more recent times of Bergen and 

 Trondhjem, and, in our own country, of Ullapool, Fort 

 William, and other places, the fortunes of all of which, 

 made by the abundance of the herring, have been often 



