It is now well enough known, even to the merest _tyros_ in the study of natural history, and to anglers and others interested as well, that the impregnation of fish-eggs is a purely external act; but at one time this was not believed, and even so lately as six years ago a portion of the experiments at the Stormontfield salmon-breeding ponds was dedicated, by Mr. Robert Buist, to a solution of this question, with what result may be easily guessed. The old theory, so stoutly maintained by Mr. Tod Stoddart and others, that it is contrary both to fact and reason that fish can differ from land animals in the matter of the fructification of their eggs, was signally defeated, and the question conclusively settled at the ponds in a very simple way—namely, by placing in the breeding-boxes a quantity of salmon eggs which had not been brought into contact with the milt, and which rotted away; proving emphatically that the sexes do not come into alliance at the time of spawning, and that there is no way of rendering the eggs fruitful unless they are brought into immediate contact with the milt. Curious ideas used to prevail on this branch of natural history. Herodotus observes of the fish of the Nile, that at the season of spawning they move in vast multitudes towards the sea; the males lead the way, and emit the engendering principle in their passage; this the females absorb as they follow, and in consequence conceive, and when their ova are deposited they are consequently matured into fry. Linnæus backed up this idea, and asserted that there could be no impregnation of the eggs of any animal out of the body, and as fish have no organs of generation, there was in the mind of the great naturalist no more feasible explanation of their mode of reproduction than that given in Beloe’s _Herodotus_. It is this wonderfully exceptional principle in the life of fish that has given rise to the art of pisciculture—_i.e._ the artificial impregnation of the eggs of fish forcibly exuded from these animals, which, as will be fully explained in another portion of this work, are brought into contact with the milt, independent altogether of the animal.