294 BRITISH FRESH-WATER FISHES 



In colour the common eel varies considerably according 

 to season and nature of habitat. Sex, also, probably affects 

 the skin tints, but that is still very uncertain, by reason that 

 the organs of reproduction are so exceedingly small while the 

 fish remains in fresh water, that it is only by aid of the 

 microscope that male and female can be distinguished. The 

 back of the fish is dark olive-green, sometimes tending to 

 brown. Below the lateral line the tints become either golden 

 or silvery, and the under-parts are white. In one respect the 

 eel is almost unique among fishes: it always seems to be in 

 good order, firm and plump if plumpness is a term applicable 

 to a creature measuring fourteen or fifteen times as much in 

 length as in depth. 



The northern limit of the eel in Europe has been fixed by 



Dr. Gttnther at 64 30' North latitude. It exists all round 



the Mediterranean, but, strange to say, is not found 



Distribution. ,, , , ~ . t ~ , A 



in the Black and Caspian Seas. On the American 

 coast of the Atlantic it meets with other species, but does not 

 extend to the Pacific watershed. In Britain it may be said 

 to exist everywhere. 



The life-history of eels has been an attractive mystery to 



man ever since he began to indulge curiosity about the ways 



of his humble fellow-creatures, yet it is only within 



Habits. , , r / - 



the Jast quarter or a century that any certain light 

 has been thrown upon their domestic arrangements. Aristotle, 

 baffled in trying to solve the enigma of their reproduction, 

 had recourse to the unphilosophic theory of spontaneous 

 generation, the outcome of putrefaction. Gesner (1516-1565) 

 could suggest nothing better, and even at this day there are 

 people in this country who believe that eels may be produced 

 by steeping horsehair (the hair of a stallion for choice) in 

 water. Yet one can scarcely afford to smile at such simplicity, 

 seeing that, down to 1896, scientific ichthyologists classed eels 

 in the larval stage as a distinct order, or at least a distinct 

 family, of fishes under the title of Leptocephalid*. It is 



