The Birmingham age-herald., 1924-09-11

was accompanied by many difficulties.
 First men. went into the fields and dusted the poison on the plants by hand. Then dusting machines, drawn by mules, were developed. Then fol- lowed power driven machines. Finally, airplanes were introduced and flew low over the fields, dusting wide areas. It was found that a single airplane would dust 500 acres an hour. Dusted cotton fields yielded $20 more to the acre than undusted fields, and it cost only 30 an acre to dust.
 One of the difficulties of the dust ing was that it must be done at night The dust would stick to damp plants but not to dry ones, This made it awkward.
 Plants POlarized
 Then a surprising discovery was made. Fields were dusted in, the day time with airplanes and with horse drawn dusting machines. The leaves of the dusted plants were then analysed by the chemists. It was found, much to their surprise, that this dust from the airplanes had stuck to the drY leaves, while that from the horse-drawn ma chimes had not stuck.
 Eventually, the reason was discov- cred. The plants were charged with electricity, as are many things in nat ure. They were polarized. The charge which they carried on the tops of their leaves was a positive charge. The par ticleS of poison dust being scattered by the airplane picked up, during the process corresponding charges of mega tive electricity. The positives attracted the negatives and the particles of poison dust were drawn into the plant, just as pin in drawn to a magnet.
 Dusting by airplanes is proceeding satisfactorily, and a modification of the process has been found which adapts it to hOrsedrawn machines. Electric generators are being attached to the machines. They supply the charge of negative electricity which the airplane dust gets from the, aaiF. Thus, it is possible to carry on the work in the daytime.
 Drawn By OdOr
 The scientists arrived at the eonclu- sion that the insects were drawn to the cotton fields by their sense of smell after long and profund research in the insect world They studied not only the boil weevil, but many other insects. They found that the male mosquito has an aIitenna, or feeler, with papillae on it like an ostrich plume. These papillae vibrate to the peculiar note of the female mosquito, when she sings on the front porch on a summer evening. They indicate her direction. He finds his mate by ear at surprising distances. With butterflies, it, is different. If yOu keep a flock of female butter flies in glass jar during the mating season with the lid screwed down, noth- ing will happen. If, on the other hand. you replace the lid with a covering that Is not air tight, you will find, in an hour, that the window will be covered with male butterflies. The sense of smell has guided them to their mates.
 It is this delicate sense of smell which guides certain insects to their food. Flowers give, off perfume to tempt bees to visit them, thus bringing pollen from OtheH flowers to fertilize them. The OdOr of the milkweed on which certain butterflies feed, or of cotton plants on which the boil weevils feed, is not strong enough to be detected by man, but these insects can smell it at great distances. It is the isolation of this OdOrOus elment' of the cotton plant that marks what may be mans final triumph over one of his most baf- fling foes.