plant to designate a vast group of objects which have no powers of locomotion, and then ask, with triumph, How can a plant move? But we have only to enlarge our knowledge of plant-life to see that locomotion is not absolutely excluded from it; for many of the simpler plants-Confervæ and Algæ-can and do move spontaneously in the early stages of their existence: they escape from their parents as free swimming rovers, and do not settle into solid and sober respectability till later in life. In their roving condition they are called, improperly enough, "zoospores,"* and once gave rise to the opinion that they were animals in infancy, and became degraded into plants as their growth went on. But locomotion is no true mark of animal-nature, neither is fixture to one spot the true mark of plantnature. Many animals (Polypes, Polyzoa, Barnacles, Mussels, etc.), after passing a vagabond youth, "settle" once and forever in maturer age, and then become as fixed as plants. Nay, human animals not unfrequently exhibit a somewhat similar metempsychosis, and make up for the fitful capriciousness of wandering youth by the steady severity of their application to business when width of waistcoat and smoothness of cranium suggest a sense of their responsibilities.

Whether this loss of locomotion is to be regarded as a retrogression on the part of the plant or animal which becomes fixed, may be questioned;

*Zoospores, from zoon, an animal, and sporos, a seed.

but there are curious indications of positive retrogression from a higher standard in the metamorphoses of some animals. Thus the beautiful marine worm Terebella, which secretes a tube for itself, and lives in it, fixed to the rock or oyster-shell, has in early life a distinct head, eyes, and feelers; but in growing to maturity it loses all trace of head, eyes, and even of feelers, unless the beautiful tuft of streaming threads which it waves in the water be considered as replacing the feelers. There are the Barnacles, too, which in the first stage of their existence have three pairs of legs, a very simple single eye, and a mouth furnished with a proboscis. In the second stage they have six pairs of legs, two compound eyes complex in structure, two feelers, but no mouth. In the third, or final stage, their legs are transformed into prehensile organs, they have recovered a mouth, but have lost their feelers, and their two complex eyes are degraded to a single and very simple eye-spot.

But, to break up these digressions, let us try a sweep with our net. We skim it along the surface, and draw up a quantity of duckweed, dead leaves, bits of stick, and masses of green thread of great fineness, called Conferva by botanists. The water runs away, and we turn over the mass. Here is a fine water-beetle, called the "Water-tiger," from its ferocity (Fig. 12). You would hardly suspect that the slim, big-headed, long-tailed Water-tiger would grow into the squat, small-headed, tailless beetle;

Fig. 12.-WATER BEETLE and its larva.

nor would you imagine that this Water-tiger would

be so "high fantas

tical" as to breathe

B

by his tail. Yet he

does both, as you will

find if you watch

him in your aqua

rium.

Fig. 13.-DRAGON-FLY LARVÆ:

A, ordinary aspect; B, with the huge nipperlike jaw extended.

Continuing our search, we light upon the fat, sluggish, ungraceful larva of the graceful and brilliant Dragon-fly, the falcon of insects (Fig. 13). He is useful for dissection, so pop him in. Among the

dead leaves you per

ceive several small leeches, and flat oval Planarice, white and brown; and here also is a jellylike mass, of pale yellow color, which we know to be a mass of eggs deposited by some shellfish; and, as there are few objects of greater interest than an egg in course of development, we pop the mass in. Here (Fig. 14) are two mollusks, Lim

næus and Planorbis, one of which is probably the

Scattered over the surface of the net and dead leaves are little dabs of dirty-looking jelly—some of them, instead of the dirty hue, are almost blood-red. Experience makes me aware that these dirty dabs are certainly Polypes—the Hydra fusca of systematists. I can't tell how it is I know them, nor how you may know them again. The power of recognition must be acquired by familiarity; and it is because men can't begin with familiarity, and can't recognize these Polypes without it, that so few persons really ever see them. But the familiarity may be acquired by a very simple method. Make it a rule to pop every unknown object into your wide-mouthed phial. In the water it will probably at once reveal its nature: if it be a Polype, it will expand its tentacles; if not, you can identify it at leisure on reaching home by the aid of pictures and descriptions. See, as I drop one of these into the water, it at once assumes the wellknown shape of the Polype. And now we will see what these blood-red dabs may be; in spite of their unusual color, I can not help suspecting them to be Polypes also. Give me the camel-hair brush. Gently the dab is removed, and transferred to the phial. Shade of Trembley! it is a Polype!* Is it possible that this discovery leaves you imperturbable, even

* TREMBLEY, in his admirable work, Mémoires pour servir à l'histoire d'une genre de Polypes d'eau douce, 1744, furnished science with the fullest and most accurate account of fresh-water Polypes; but it is a mistake to suppose that he was the original discoverer of this genus: old LEUWENHOEK had been before him.