Page:Popular Science Monthly Volume 89.djvu/209

 Popular Science Monfhh/

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��A New Garden Duster Which Uses Dry Spray

TIIIC iiso of dry s[)ra\s iiislcad of liiiuiil poisons is roining into favor ainonji gank-n niaicers because they in- volve less work, are not so dirty and are ready for instant use. A new hand duster for aj^pKing dry sprays is novel in principle as well as design and is by far the most efficient de\"ice which has yet been in\'cntcd. The powder is contained in a large metal reservoir, within which the pumj) mechanism acts. Kach mcne- ment of the jiiston automatically meas- ures and ejects an amount of dust regu- lated b\' the force imparled to the jiiston. It is double acting and will throw a cloud of dust or powder up or down or in any other direction. With this new duster a single puff of arsenate of lead will com- pletely co\er a potato plant with the poison. All vegetables and small fruits and even low trees may be quickly sprayed with poison or with sulphur with a minimum of effort.

The duster may also be used as a house disinfectant, discarding the arse- nate of lead for a non-poisonous liquid or powder. No corner is beyond reach of the duster, and the acids used as sprays do not injure it.

��How the Snail's Tongue Cleans the Aquarium

����The liquid is forced into the recesses of vegetables, small fruits and low trees

��The snail has a tongue which closely re- sembles the teeth on a carpenter's rasp

EVERY one who keeps an aquarium knows that it is advisable to place a few snails in the tank, not only be- cause snails are interesting in themselves, but because they are good cleaners. If the keeper of the aquarium knows that too much sunlight will produce too much plant growth, and has placed the vessel in a partly shaded place where the pro- portion of light and shade is about right, the snails, if they are numerous enough, can then control the growth. They creep along the side of the aquarium, as if they were idling away their time and merely crawling around to call on their neigh- bors. In reality the\' are not dreamers but scavengers.

Nature hiis provided them with a peculiar anatomical structure resem- bling a narrow ribbon, which in detail is like the band of teeth on a carpenter's rasp, lender the microscope these so- called "lingual ribbons" or tongues are seen to be thickly set with rows of sharp-edged teeth which arc themselves lOfjthed and which rasp off microscopic ])lants and carry them into the mouth.

The accompanying illustration is from a marine form known as the "blcoding- teeth" snail. In the original the ribbon has a bright reddish color as if it had been dipped in blood. When the image is thrown on the screen by the projection microscope, it resembles a huge red rasp three or four feet in diameter and extend- ing across the entire width of the screen.

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