INTRODUCTION 



water, an Eel is about 3j inches long, at 5 years it is 

 about 6 inches, at 8 years about 1 foot, and at 13 years 

 nearly 2 feet in length. 



Eels do not spawn in fresh waters. When the 

 period of maturity approaches and with it the repro- 

 ductive impulse, at the age of from 6 to 10 years, 

 they become silvery in appearance (" Silver-eels "), 

 their eyes become larger, and they make for the 

 rivers in which they descend to the sea. Having 

 reached the sea they travel oceanwards, at an average 

 rate of more than 9 miles a day, on their final journey 

 — pour V amour et pour la morl — of over 2000 miles to 

 their breeding-ground in the depths of the Atlantic 

 Ocean, where they spawn and die. 



The occurrence of Eels in land-locked waters, which 

 seemed to complicate the problem of their origin and 

 mode of propagation, is explained by the ability of 

 the Eel to exist for a considerable time out of the 

 water (A. 592 a 13, PUn. ix. c. 38) and to the agility of 

 the young Eels in travelUng for some distance over- 

 land (A. Part. An. 696 a 5, Theophrast. iripX i-^dvwv 

 Twv Iv Tw ^>//3w Starpi/iovTojv fr. 171), and so making 

 their way even into waters from which the adult Eels 

 under the reproductive impulse in vain endeavour 

 to escape. On the other hand there are no Eels in 

 the Danube, nor in the Black Sea or the Caspian Sea, 

 these waters being beyond the reach of the young 

 Eels migrating from the Atlantic Ocean. 



Cf. J. Schmidt, " The Breeding-place of the Eel," 

 Ann. Rep. Smithsonian Inst. Washington, 192 1 [1925], 

 pp. 279-316 ; C. Rabot, " Les Anguilles du Pacifique," 

 Nature, Paris, 1926, pp. 113-118 ; K. Marcus, '^ tJber 

 Alter und Wachstum des Aales," Jahrh. Hamburg 

 miss. Anst. xxxvi (1919), pp. 1-70. 



Ixxiii 



