296 BRITISH FRESH-WATER FISHES 
has been well established, we are far from being complete 
masters of the eel mystery. The elvers ascend the streams 
all round our coasts, penetrating to the remotest lakes and 
the most secluded pools, frequenting the channels of the 
greatest rivers as well as the wayside ditch. Wherever a 
living is to be made under water, there you may reckon 
upon good store of eels, but of their rate of growth nothing 
is known. Neither has it been ascertained how long they 
remain in fresh water ; only this is certain, that a time comes 
when an exodus takes place seaward. Nota migration of the 
whole eel population, as is the case with salmon and smelts; 
only of those individuals which begin to feel the sexual 
impulse. In the autumn months these begin dropping down 
the rivers, when they are taken in large numbers by “ eel- 
bucks”’—wicker baskets fashioned inside like a mouse-trap 
and set in a wooden framework across the stream. 
The question has often been discussed whether eels ever 
return to the river after spawning in the sea. Probably they 
do not, for there is no trustworthy evidence to that effect, 
and the acumen of fishermen may generally be trusted to 
detect the seasonal movements of their game. It seems most 
likely that eels remain in fresh water for an indefinite number 
of seasons, till the generative impulse makes itself felt, when 
they at once go to the sea. There the development of the 
organs of reproduction is very rapid, and the exhaustion 
after the act of reproduction so great that both sexes die, 
having fulfilled the primary law—increase and multiply. The 
number of eggs in the ovary of a female eel thirty-two inches 
long has been computed at ten millions seven hundred thousand. 
In the complete absence of all evidence to the contrary, 
it may be assumed that it is only in salt water that eels can 
spawn. This seemed to be hard to reconcile with the fact 
that throughout the long period, sixty or seventy years, when 
the Thames was closed by pollution to fish from the sea. 
eels continued abundant in that river above the tideway. So 
