As I promised you that I would communicate to you, from time to time, any new remarks or facts which might occur on the subject of naturalizing sea-fish in fresh water, I am pleased to have an opportunity of noticing a few circumstances which may serve to keep alive in the public mind a subject, from which I cannot yet help foreboding useful results, in spite of the neglect and opposition which it has experienced from every person, I believe I may safely say, to whom it has been proposed, except Mr. Arnold. I am perfectly safe in saying, that, with this sole exception, every individual to whom the facts have been described, and the experiment proposed, have replied by doubts, or cavils, or objections of some kind; many, by [p321] positive disbelief of the very facts; while the far greater number have been persons, whose entire ignorance of every requisite point of physiology, natural history, and chemistry, must, of course, have rendered their objections sufficiently unworthy of notice, though not sufficient to restrain the confidence with which they have been urged. The satirical writers of the day view this as the character of the age: the more obvious aspect which this disposition presents, is the feeling, as if he who attempted, by suggesting an improvement, to render a service, was meditating an injury, and was an enemy to be opposed at all hazards. I must permit you to settle metaphysical and moral questions so profound as to exceed my own ingenuity. But I cannot avoid regretting that Mr. Arnold is not the rich and idle proprietor of some of the tens of thousands of acres of fresh water, whether Scotch or English, in which a ‘sea-fish cannot possibly live,’ or ‘would certainly not be eatable’: and, in addition, that, instead of a not very opulent and very busied ‘notary public,’ he was not in possession of some five thousand of these acres, with as much money, and as much leisure. And I feel bound to add to this apology for what he _has not_ yet done, that the expense of such a course of experiments is considerable; at least in this comparison. A superintendent would be necessary; and for the purpose of taking and transporting the fish, still more of drawing nets periodically and frequently, to ascertain the progress of the transplanted fish, there must be expensive assistance, for which, as yet, there can be no returns; while that, in addition to irregularities and rocks in the pond itself, impeding the accurate drawing and examination, must also be the apology for the imperfection of the present additional report as to the success for certain fishes. It is plain that, though ten or a hundred turbots were present in a pond of four or five acres, the fact is not one that can easily be ascertained. Let those who have money, leisure, and water, and nothing else towards the investigation of this object, restrain, at least, _their_ incredulity and opposition; as may also they, very safely, who never saw a fish, except on the stall of a