210 Dr. Mac Culloch on the changing 
interesting nature, concern the means of transferring the inhabi- 
tants of fresh waters in one country, or those of certain lakes or 
rivers, to others where they are not found, some hints are also 
introduced respecting the possibility of rendering certain sea-fish in- 
habitants of fresh waters. The whole paper is highly worthy of 
attention ; but I am not aware thatit has been followed by any of the 
practical trials recommended by the author, on which its economical 
value must ultimately depend. An example in point which recently 
came under my notice in Shetland, has induced me to examine the 
subject with somewhat more care than the author of that memoir 
seems to have bestowed on it, and to inquire more minutely into the 
arguments on which the probability of success rests. The following 
seem to be the only results which have been obtained, or were pre- 
viously known with respect to that part of M. Nouel’s plan, which 
relates to the cultivation of sea-fish in fresh water. 
The plaice, Pleuronectes Platessa, as it appears, has been carried 
from the North sea to the ponds of East Friesland, where it has 
become established. The herring is said by Liancourt to frequent 
the Potowmack, Hudson, Elk, and Delaware rivers; but it has not 
appeared that the author’s project to take it from the Seine into 
fresh-water ponds has been put into practice. The authority of 
Twiss for the existence of this fish in the fresh water lakes of Ire- 
land, is more than questionable, and M, Nouel is assuredly misin- 
formed when he states that it is found in prodigious shoals in Loch 
‘Lomond and Loch Eck in Scotland, both of them fresh inland 
lakes. I know not how this author can have thus been misled, 
unless he has mistaken some of the sea lochs for fresh-water lakes ; 
though he could scarcely have confounded those he has named 
with any of the western inlets. I shall hereafter, however, point 
out a fact which renders his assertion possible; though he could not 
have been acquainted with it, as it is not very long since it was 
known, and has not been published in any work siioiglt to have 
reached his hands. 
It is also asserted in the same paper, that the salmon, in sual 
has, in certain lakes, become naturalized, ‘‘ abandoning their erra- 
tic taste, for a calm and settled life.” Whether such an experiment 
