352 ZOOLOGY. 



shores, and give rise to important fisheries. The salmon is 

 also equally remarkable for its journeys or voyages. It in- 

 habits all the Arctic Seas, and each spring it enters the rivers 

 in vast troops, to ascend them even to their sources. In 

 these emigrations the salmon follow a regular order, forming 

 two long tiles, reunited in front, conducted by the largest 

 female, which precedes, whilst the small males form the rear- 

 guard. These troops swim in general with much noise, 

 in the middle of rivers, and near the surface of the water if 

 the temperature be mild, but nearer the bottom if the heat be 

 great. In general, salmon advance slowly, sporting as they 

 proceed ; but if danger appears to threaten them, the rapidity 

 of their course becomes such that the eye can scarcely follow 

 them. If a dyke or cascade opposes their progress, they make 

 the greatest efforts to overcome it. Resting on some rock, 

 and extending the body suddenly and with violence, after 

 being curved, they spring out of the water, leaping occa- 

 sionally to the height of four or five metres (fifteen feet) in 

 the air, and so as to fall beyond the obstacle which stops them. 

 Salmon ascend rivers even to their source, and search in the 

 small streams and tranquil places a bottom of sand and 

 gravel adapted for the deposition of their eggs. Then, feeble 

 and thin by such fatigue, they descend in autumn towards 

 the mouth of the rivers, in order to pass their winter in the 

 sea. The eggs are deposited in a trough dug by the female 

 in the sand; they are afterwards fecundated by the male. 

 The young salmon grow very rapidly ; and when they are 

 about a foot long, they leave the rivers to repair to the sea, 

 which they quit in its turn to again enter the rivers, when 

 they are about four or five decimetres in length (from sixteen 

 to twenty inches), that is to say, towards the middle of the 

 summer that followed their birth. We have already seen 

 that the swallows, which at the approach of the cold season 

 emigrate to the south, return annually to the same places. 

 It appears that salmon have the same instinct. To be assured 

 of it, a naturalist of the name of Deslandes put a copper ring 

 in the tail of twelve of these fishes, and restored them to 

 liberty in the river Auzou in Brittany. Soon afterwards they 

 all disappeared, but the year following they caught in the 

 same place five of these salmon ; in the second year three, and 

 in the year following still three. 



[The sardine, the mackerel, the tunny, the anchovy, and 

 the sprat, are also fish of passage, which periodically visit 



