New Monthly Magazine.

* * * * *

NOTES OF A READER.

* * * * *

EELS.

The problem of the generation of eels is one of the most abstruse and curious in natural history; but we have been much pleased, and not a little enlightened, by some observations on the subject in Sir Humphrey Davy’s delightful little volume, Salmonia, of which the following is the substance:—­

Although the generation of eels occupied the attention of Aristotle, and has been taken up by the most distinguished naturalists since his time, it is still unsolved.  Lacepede, the French naturalist, asserts, in the most unqualified way, that they are viviparous; but we do not remember any facts brought forward on the subject.  Sir Humphrey then goes on to say—­This is certain, that there are two migrations of eels—­one up and one down rivers, one from and the other to the sea; the first in spring and summer, the second in autumn or early winter.  The first of very small eels, which are sometimes not more than two or two and a half inches long; the second of large eels, which sometimes are three or four feet long, and which weigh from 10 to 15, or even 20 lbs.  There is great reason to believe that all eels found in fresh water are the results of the first migration; they appear in millions in April and May, and sometimes continue to rise as late even as July and the beginning of August.  I remember this was the case in Ireland in 1823.  It had been a cold, backward summer; and when I was at Ballyshannon, about the end of July, the mouth of the river, which had been in flood all this month, under the fall, was blackened by millions of little eels, about as long as the finger, which were constantly urging their way up the moist rocks by the side of the fall.  Thousands died, but their bodies remaining moist, served as the ladder for others to make their way; and I saw some ascending even perpendicular stones, making their road through wet moss, or adhering to some eels that had died in the attempt.  Such is the energy of these little animals, that they continue to find their way, in immense numbers, to Loch Erne.  The same thing happens at the fall of the Bann, and Loch Neagh is thus peopled by them; even the mighty Fall of Shaffausen does not prevent them from making their way to the Lake of Constance, where I have seen many very large eels.  There are eels in the Lake of Neufchatel, which communicates by a stream with the Rhine; but there are none in the Lake of Geneva, because the Rhone makes a subterraneous fall below Geneva; and though small eels can pass by moss or mount rocks, they cannot penetrate limestone rocks, or move against a rapid descending current of water, passing, as it were, through a pipe.  Again:  no eels mount the Danube from the Black Sea; and there are none found in the great extent of lakes, swamps,