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Page:Popular Science Monthly Volume 35.djvu/338

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318
THE POPULAR SCIENCE MONTHLY.

I let the water run out of the net into a small glass, so as to be sure that it contains no other animals, and take a glass tube long enough easily to reach the bottom of the mug. The life here is all in a confusion of panic on account of the cramped quarters. I introduce the tube, holding the upper end tightly closed with my forefinger. The air contained within it permits very little water to enter.

We have now to keep a sharp lookout. When I perceive a butterfly which perhaps has sprung at a bound to the surface and is now gently sinking back, I try to bring the lower end of my tube close to it. My forefinger is then suddenly raised; a stream of water, stronger as the tube is deeper in, presses out the escaping air and draws the animal in with it. My forefinger is then brought down to close the upper end, the tube is drawn out, and the animal in it is transferred to the collecting-glass. This is a simple method of catching such small and delicate animals, but must be well practiced if one would acquire any skill in it. It can not be used successfully in a rough sea, and when that is the condition the student must wait till he gets home. But when the animal is secured, it is a real joy to lose one's self in contemplating it with the lens and microscope. The needle-butterflies are a beautiful object. Their cylindrical, glass-clear shell is firm enough to stand a slight pressure. An animal is caught in the prescribed way and put in a compressorium; a small instrument, a thin glass-plate or cover, is used with a tortuous movement to bring it closer up on the stand, which is also of glass. A drop of water is made to fall on the stand, the creature to be examined is brought up, and the two plates are twisted till both touch the drop. We might crush our specimen with the apparatus; but we carefully regulate the pressure so that no harm shall come to it while it is held fast in the same place. It struggles, beating with its wings, but all its exertions are in vain; it can not in the narrow space overcome the pressure that weighs upon its shell.

It is a wonderful view we get under the microscope of the fine muscular fibers crossing one another in the wings, now drawing together and now extending out, and we can follow the ramifications of the nerves and the vessels of the circulation. We perceive the motions of the mouth as it opens and shuts, the pharynx-head with the tongue, which is projected and withdrawn, the connections of the intestine; we see the heart beat, and can follow the current and eddies of water which are produced in the breathing pores and certain secretory openings by the beating of innumerable cilia in their regular way. The animals are hermaphrodite. We can see the eggs and other products in the organs where they are generated and in the channels through which they are expelled. Only a few hours passed before the needle-butterflies and