THE SALMON, THE TROUT, AND THE SHAD. 745 



remnants of food had been caught near Wesel. The food may there- 

 fore have been taken partly in the mouth of the Rhine and partly in the 

 ocean. 



I will here mention an interesting observation, which was communi- 

 cated to me by the Messrs. Bidder and Lindner. The Dutch fishermen 

 have occasionally found in the stomachs of those salmon which were 

 caught near the mouth of the Ehine remnants of fish which they said 

 came from the herring {Clupea liarengus). But, according to the unani- 

 mous testimony of the fishermen, there never were found remnants of 

 fish or any other food in the stomachs of salmon which had ascended 

 higher up the Ehine. This observation agrees in every particular with 

 those made by me. 



These investigations therefore lead me to the following result: Trutta 

 salar and Trutta trutta, while in the Ehine, do not take food at any 

 season of the year, which explains the fact that all attempts to keep 

 salmon and raise them artificially in fresh water have proved failures. 1 

 There are artificial hatching-establishments (e. g., in Hiiniugeu, near 

 Strasburg, and in Arnheim) where the ripe salmon-eggs are artificially 

 impregnated and hatched, and where the young salmon, called Salmlinge, 

 [in English samlets,] obtained in this manner, are kept for some time 

 (perhaps one to three years) ; but, if these fish are to become full-grown 

 salmon, they must be let loose so that they can reach the ocean, there 

 to feed and grow. A friend of mine communicated to me the following: 

 The institution near Arnheim, on the Yssel, has, during this spring, arti- 

 ficially raised 300,000 young salmon and placed them in the Yssel. 

 These are to go to the ocean, return to the Yssel 2 during the following 

 years, and then be caught as salmon. The young salmon are fed in the 

 water of the Yssel, which is pumped into reservoirs from the river, and 

 then led through the tanks in which the fish are kept. They are not 

 supplied with any food, but find it in the water (infusoria, larvae, &c.) 

 If these young salmon are to be sent away, they are placed in special 

 boxes, and fed on calves' brain and worms. 



The following observation, communicated by Sander in the " Naturfor- 

 scher," 3 is explained in the same manner: "A reliable fisherman kept 

 young salmon for many years, and fed them — on what % Unfortunately, 

 he did not inform me. He paid great attention to them, but found that 



1 G Untlier says on this point, (p. 9:) "The question "whether any of the migratory 

 species (of the genus Sahno) can he retained in fresh water, and finally accommodate 

 themselves to a permanent sojourn therein, must be negatived for the present." 



2 It may be considered as an established fact that the salmon return to the river in 

 which they were born and raised. In Brittauy, a dozen young salmon were marked 

 with copper rings on the tail. Of these, five were caught in the following year, three 

 in the second, and three in the third. — (Cornelius, Zng- and Wanderthiere, Berlin, 1865, 

 p. 202.) During the summer of 1873, 500 youug salmon, twenty-one months old, 5 to 

 6 inches long, were marked and placed in the Rhine, in order to ascertain whether they 

 will return to the same river. — (From a newspaper.) 



3 Der Naturforscher, 15. Stuck, 1781, p. 170. 



