the Residence of certain Fishes. 223 
spect to the plaice, mullet, and flounder; and it is only to be regret- 
ted that no further evidence of this satisfactory nature can be 
adduced in favour of this reasoning. The double residence, how= 
ever, of the pike, and of the various Cyprini, already more than 
once quoted, offers a complete argument in favour of the convertible 
habits of these species at least, in the business of reproduction as in 
that of food. 
Supposing now that, at least the probability of all these reason= 
ings is admitted, it only remains to put these speculations to the 
test of more extensive experiments. Nature has executed two, per- 
haps more; art, in the plaice, the smelt, and the mullet, has carried 
three more into effect. There appears no practical difficulty attending 
it ; as fish can be transported alive in water, for a great length oftime, 
and to great distances, without inconvenience. If Shetland were differ- 
ently constituted with respect to the distribution ofits population and 
the residence of its proprietors, a very satisfactory and easy experi= 
ment, on the cod at least, might be made in Stromness Voe. It 
would only be necessary to shut up the very narrow opening by 
which it communicates with the fresh water, by means of a grating, 
and time alone would soon determine the question. Should this 
paper meet the eyes of a body of proprietors distinguished for their 
intelligence and activity, it may perhaps iuduce him in whose power 
it lies, to make this easy experiment. Nor could there, in this 
place, as in some other situations in Scotland, be any difficulty in 
extending the same trials to other species of fish. But I need not 
dwell on this part of a subject which every one is competent to un= 
derstand, but which not many have the means of submitting to the 
test of experiment. 
On the transportation of fish, I must remark thatit is not attended 
with so much difficulty as is commonly imagined, and that the fault 
generally has lain with those who have made the attempts. Many 
' fish are exceedingly tolerant of being out of water fora time. The 
carp is keptin nets, in cellars, and fed thus in Holland. Minnows 
will live for months, crowded in a quart pot, with as little water as 
they can barely stir in, or in absolute contact. The whole of the 
flat fish are similarly tenacious of life; as are the conger, the gur- 
R 2 
