instinctively bury themselves in damp ground, and I therefore instituted a series of experiments by placing the newly-emigrated worms in flower-pots filled with damp earth. To my delight, I soon perceived that they began to bore with their heads into the earth, and by degrees drew themselves entirely in. For many months I kept the earth in the flower-pots moderately moist, and, on examining the worms from time to time, I found they had gradually attained their sex-development, and eggs were deposited in hundreds. Toward the conclusion of winter I could succeed in detecting the commencing development of the embryos in these eggs. By the end of spring they were fully formed, and many of them, having left their shells, were to be seen creeping about the earth. I now conjectured that these young worms would be impelled by their instincts to pursue a parasitic existence, and to seek out an animal to inhabit and to grow to maturity in; and it seemed not improbable that the brood I had reared would, like their parents, thrive best in the caterpillar. In order, therefore, to induce my young brood to immigrate, I procured a number of very small caterpillars, which the first spring sunshine had just called into life. For the purpose of my experiment, I filled a watch-glass with damp earth, taking it from among the flower-pots where the thread-worms had wintered. Upon this I placed several of the young caterpillars." The result was as he expected; the caterpillars were soon bored

into by the worms, and served them at once as food and home.*

Frogs and parasites, worms and infusoria—are these worth the attention of a serious man? They have a less imposing appearance than planets and asteroids I admit, but they are nearer to us, and admit of being more intimately known, and, because they are thus accessible, they become more important to us. The life that stirs within us is also the life within them. It is for this reason, as I said at the outset, that, although man's noblest study must always be man, there are other studies less noble, yet not therefore ignoble, which must be pursued, even if only with a view to the perfection of the noblest. Many men, and these not always the ignorant, whose scorn of what they do not understand is always ready, despise the labors which do not obviously and directly tend to moral or political advancement. Others there are who, fascinated by the grandeur of Astronomy and Geology, or by the immediate practical results of Physics and Chemistry, disregard all microscopic research as little better than dilettante curiosity. But I can not think any serious study is without its serious value to the human race; and I know that the great problem of Life can never be solved while we are in ignorance of its simpler forms. Nor can any thing be more unwise than the attempt to limit the sphere

*VON SIEBOLD: Ueber Band-und-Blasenwürmer. Translated by HUXLEY.

of human inquiry, especially by applying the test of immediate utility. All truths are related; and, however remote from our daily needs some particular truth may seem, the time will surely come when its value will be felt. To the majority of our countrymen during the Revolution, when the conduct of James seemed of incalculable importance, there would have seemed something ludicrously absurd in the assertion that the newly-discovered differential calculus was infinitely more important to England and to Europe than the fate of all the dynasties; and few things could have seemed more remote from any useful end than this product of mathematical genius; yet it is now clear to every one that the conduct of James was supremely insignificant in comparison with this discovery. I do not say that men were unwise to throw themselves body and soul into the Revolution; I only say they would have been unwise to condemn the researches of mathematicians.

Let all who have a longing to study Nature in any of her manifold aspects do so without regard to the sneers or objections of men whose tastes and faculties are directed elsewhere. From the illumination of many minds on many points Truth must finally emerge. Man is, in Bacon's noble phrase, the minister and interpreter of Nature; let him be careful lest he suffer this ministry to sink into a priesthood, and this interpretation to degenerate into an immovable dogma. The suggestions of

apathy and the prejudices of ignorance have at all times inspired the wish to close the temple against new comers. Let us be vigilant against such suggestions, and keep the door of the temple ever

open.

CHAPTER II.

Ponds and Rock-pools. Our necessary Tackle.- Wimbledon Common.-Early Memories.- Gnat Larvæ.- Entomostraca and their Paradoxes.-Races of Animals dispensing with the sterner Sex.-Insignificance of Males.-Volvox Globator: is it an Animal?-Plants swimming like Animals.-Animal Retrogressions.—The Dytiscus and its Larva.-The Dragon-fly Larva.-Mollusks and their Eggs.-Polypes, and how to find them. -A new Polype, Hydra rubra.-Nest-building Fish.-Contempt replaced by Reverence.

THE day is bright with a late autumn sun; the sky is clear with a keen autumn wind, which lashes our blood into a canter as we press against it, and the cantering blood sets the thoughts into hurrying excitement. Wimbledon Common is not far off; its five thousand acres of undulating heather, furze, and fern tempt us across it, health streaming in at every step as we snuff the keen breeze. We are tempted also to bring net and wide-mouthed jar, to ransack its many ponds for visible and invisible wonders.

Ponds, indeed, are not so rich and lovely as rockpools; the heath is less alluring than the coastour dear-loved coast, with its gleaming mystery, the sea, and its sweeps of sand, its reefs, its dripping boulders. I admit the comparative inferiority of ponds, but, you see, we are not near the coast, and