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Part III. — Thirteenth Annual Report 



whose total length is less than 29-33 cm., for with those two lengths the 

 two sexes become capable of reproduction. The change from the yellow 

 to the silver colouration takes place rapidly — in a few weeks. 



The Migration of the Eel. 



1 Hiring autumn the great majority of the adult eels leave the streams 

 and rivers and migrate to the sea. Some of the eels, however, remain in 

 fresh water during the winter. That this migration to the sea is for the 

 purpose of spawning is conclusively proved by the fact that about the 

 end of spring and beginning of summer, immense numbers of young eels 

 enter the fresh water streams from the sea. While most authorities are 

 agreed that the eels spawn only in salt water, some are of the opinion that 

 they also spawn in fresh water. Roosevelt * maintained that eels were 

 hatched in fresh water in his trout ponds in Great South Bay, Long 

 Island. Sawyer f also considered that the eels do not all return to salt 

 water to spawn, but spawn wherever they find suitable places in ponds 

 and rivers. A description of the spawning of the eel is given by the 

 Rev. J. E. Fraser.J From the following extract it appears pos- 

 sible that the observer has mistaken the lamprey for the eel. The 

 spawning was observed 1 in an old stream which has not been known 



* to run dry, and about a dozen yards from the lake Lochness, 

 ' into which the burn flows. The time or season was early in May, 

 1 and for three weeks in June. The establishment consisted of four 

 1 males and two females. The female adhered to or attached her head 



* (mouth) to a firm stone or pebble, then the male fixed himself to her 

 ' head by suction or pressure, and put one coil of his tail around the middle 

 1 of her body, then slid or glided down that section until it reached the 

 1 desired spot. From the moment of connection there is a very lively play 

 ' of tails, and so strong as to disturb the coarse sand and ova recently 

 ' deposited. The female apparently passes four or five eggs simultaneously 

 ' with the withdrawal of the male organ. The ova, as a rule, fell to the 

 ' bottom, and lay on the coarse sand or pebbles as small white globular 

 ' bodies.' No further description of the ripe egg is given in the report. 

 In this connection Benecke § says that ' eels planted in land-locked ponds 

 1 increase in size, but never increase in numbers. In lakes which formerly 

 ' contained eels, but which by the erection of impassable weirs, have been 

 1 cut off from the sea, the supply has diminished, and after a time only 

 ' scattered individuals, old and of great size, are taken in them. If an 

 1 instance of the reproduction of the eel in fresh water could be found, 

 ' occurrences such as these would be quite inexplicable.' At the meeting 

 of the Scottish Microscopical Society on the 16th of February 1894, Mr 

 George Sandeman called attention to some remarkable eels from a warm 

 and stagnant loch on the Isle of May, which has no communication with 

 the sea. He remarked that it was not known how long ago the eels 

 were placed in the loch, but it did not appear to have been within the 

 memory of man. They are not known to breed, their ovaries and testis 

 being somewhat atrophied, though still apparently functional. In the 

 specimens examined, atrophy is also marked in the muscles, liver and 

 spleen. The ovaries and ova are very small, fatty, and the nuclei of the 



* Trans, of the American Fish. Cultural Assoc., 7 th Meet., 1878. 

 t Bulletin U.S. Fish. Commission, vol. vi., 1886. 



J 'Notes on the Spawning of the Angtiillidce,' Report of Brit. Assoc, for Adv. of 

 Science, 60th Meet., 1890. 



§ Brown Goode ' Notes on the Life History of the Eel,' Bulletin U.S. Fish. 

 Comm., vol. i., 1881. 



