THE FRESH WATERS 165 
at the other side of the room, apparently 
dead; however, when returned to the water 
they swam about apparently none the worse 
for their excursion.” Once settled down in 
suitable quarters the elvers begin to feed and 
to grow, and are now known as “ yellow eels.” 
Their food consists at first of worms, larve, 
and small fishes, but as they grow they become 
very voracious, and will attack water voles 
and water-fowl, and even larger fishes, among 
which they do serious damage. There is even 
a case on record of an eel, 5 feet long, which 
attacked a swan! The owner saw the swan 
struggling violently, with its head under 
water. He went to its assistance and found 
that its head had been seized by a large eel, 
which held on so obstinately that it allowed 
itself to be caught and landed. 
About the third summer of an eel’s life in 
fresh water its scales begin to grow. It is an 
interesting fact that naturalists can tell the 
age of an eel, or at least the length of time it 
has spent in fresh water, by examining its 
scales under the microscope. Each scale is 
arranged in little zones or rings studded with 
tiny, limy knobs, separated by narrow rings 
of smooth material. ‘This structure is due 
