It may, possibly, be by the use of their arms, which form the first ray of the pectoral fin." There is another operation by fishes, which seems to require almost equal experience. Professor Agassiz, while collecting insects along the shores of Lake Sebago, in Maine, observed a couple of Cat-fish, which, at his approach, left the shore suddenly, and returned to the deeper water. Examining the place which the fishes had left, he discovered a _nest_ among the water-plants, with a number of little tadpoles. In a few moments the two fishes returned, looking anxiously towards the nest, and approached within six or eight feet of where Professor Agassiz stood. They were evidently not in search of food, and he became convinced that they were seeking the protection of their young. Large stones, thrown repeatedly into the middle of the nest after the fishes had returned to it, only frightened them away for a brief period, and they returned to the spot within ten or fifteen minutes. This was repeated four or five times with the same result. This negatives the assertion made by some naturalists--that no fishes are known to take any care of their offspring. But affection is scarcely to be looked for where the offspring is so very numerous as to put all attempts at even recognising them out of the question. How could the fondest mother love 100,000 little ones at once? Yet the number is far exceeded by some of the matrons of the deep. Petit found 300,000 eggs in a single carp; Lenwenhoeck 9,000,000 in a single cod; Mr. Harmer found in a sole 100,000; in a tench 300,000; in a mackerel 500,000; and in a flounder 1,357,000.[14] M. Rousseau disburthened a pike of 160,000, and a sturgeon of 1,567,000, while from this latter class has been gotten 119 pounds weight of eggs, which, at the rate of 7 to a grain, would give a total amount of 7,653,200 eggs! If all these came to maturity the world would be in a short time nothing but fish: means, however, amply sufficient to keep down this unwelcome superabundance have been provided. Fish themselves, men, birds, other marine animals, to say nothing of the dispersions produced by storms and currents, the destruction consequent on their being thrown on the beach and left there to dry up, all combine to diminish this excessive supply over demand. Yet, on the other hand (so wonderfully are all the contrivances of nature so harmonized and balanced), one of these apparent modes of destruction becomes an actual means of extending the species. The eggs of the pike, barbel, and many other fish, says M. Virey, are rendered indigestible by an acid oil which they contain, and in consequence of which they are passed in the same condition as they were swallowed; the result of which is, that being taken in by ducks, grebes, or other water-fowls, they are thus transported to situations, such as inland lakes, which otherwise they could never have attained; and in this way only can we account for the fact, now well ascertained,