the result of scientific knowledge or reason, though depending upon a more unerring principle, their instinct for preserving their offspring.  Those fishes that spawn in spring or the beginning of summer and winch inhabit deep and still waters, as the carp, bream, pike, tench, &c., deposit their eggs upon aquatic vegetables, which by the influence of the solar light constantly preserve the water in a state of aeration.  The trout, salmon, hucho, and others of the Salmo genus, which spawn in the beginning or end of winter, and which inhabit rivers fed by cold and rapid streams which descend from the mountains, deposit their eggs in shallows on heaps of gravel, as near as possible to the source of the stream where the water is fully combined with air; and to accomplish this purpose they travel for hundreds of miles against the current, and leap over cataracts and dams:  thus the Salmo salar ascends by the Rhone and the Aar to the glaciers of Switzerland, the hucho by the Danube, the Isar, and the Save, passing through the lakes of the Tyrol and Styria to the highest torrents of the Noric and Julian Alps.

Phil.—­My own experience proves in the strongest manner the immediate connection of sensibility with respiration; all that I can remember in my accident was a certain violent and painful sensation of oppression in the chest, which must have been immediately succeeded by loss of sense.

Eub.—­I have no doubt that all your suffering was over at the moment you describe; as far as sensibility is concerned, you were inanimate when your friend raised you from the bottom.  This distinct connection of sensibility with the absorption of air by the blood is, I think, in favour of the idea advanced by our friend, that some subtle and ethereal matter is supplied to the system in the elastic air which may be the cause of vitality.

The Unknown.—­Softly, if you please; I must not allow you to mistake my view.  I think it probable that some subtle matter is derived from the atmosphere connected with the functions of life; but nothing can be more remote from my opinion than to suppose it the cause of vitality.

Phil.—­This might have been fully inferred from the whole tenor of your conversation, and particularly from that expression, “that which commands sensation will not be their subject.”  I think I shall not mistake your views when I say that you do not consider vitality dependent upon any material cause or principle.

The Unknown.—­You do not.  We are entirely ignorant on this subject, and I confess in the utmost humility my ignorance.  I know there have been distinguished physiologists who have imagined that by organisation powers not naturally possessed by matter were developed, and that sensibility was a property belonging to some unknown combination of unknown ethereal elements.  But such notions appear to me unphilosophical, and the mere substitution of unknown words for unknown things.  I can never