The educational screen (c1922-c1956])

176 The Theatrical Field 1 he Jbaucational Screen though nothing out of the ordinary had happened. The Fly as a Disease Carrier. (Bray.) Models of the common housefly are shown — particularly those parts of his anatomy most concerned in the carrying of disease. Excellent microscopic views of the feet show the structure especially equipped for collecting dirt and disease germs. A fly is allowed to walk over a gelatin plate, and somewhat later the plate shows colonies of bacteria grown from the dirt left on the gelatin. Some of the favorite breeding places of the fly are pictured. His sucking proboscis is seen in enlarged view, and diagrammatic animation shows the action of the liquids secreted in his "body — these liquids making it possible for him to dissolve substances, and expel the liquid from his crop. Germs collected from fly specks are incubated, showing tuberculosis. A chart indicates the relation of intestinal diseases to flies — testimony borne out bj' the fact that deaths from typhoid are found to be immensely greater during the fly season. In order to carry on a campaign of extermination, it is necessary to discover their breeding places. The eggs, white larvae, and pupae are splendidly shown. A table of figures giving the rate of increase during three months' time demonstrates the fact that any campaign to exterminate must get in its work before the flies are ten days old. Various methods are suggested, and the film closes with the slogan: "Make Your Community Flyless." Animal Camouflage. (Pathe.) Protective coloration, or — perhaps more accurately — protective mimicry, causes many animals to blend so perfectly with their surroundings as to make detection almost impossible. Many examples are given: of the hermit crab which crawls into the shell of another sea animal, and other crabs covering themselves with the refuse of the sea floor; of worms; and, one of the most perfect mimics of all, the walking stick — its whole body structure imitating the form of twigs over which it crawls, so that only by its movement is it possible to detect which is the walking stick and which is the twig. The praying mantis, one of the deadliest of insects, which feeds on animal and vegetable life, is shown in detail, particularly as to the structure of the neck and the sturdy forelegs which he uses as his deadly weapons, and carefully cleans after a battle with his prey. The locust resembles rock surfaces to which it clings, and the tree toad and desert lizard also furnish further illustrations of protective coloration as a means of defense. There is also a "warning coloration" which marks such insects as the Monarch Butterfly, which is distasteful to other animals. Other butterflies in turn are protected by resembling the Monarch in hue and pattern. The reel closes with illustrations of the walking leaf of the East Indies, which the natives declare is really a transformed leaf. A study of one of nature's most interesting adaptations for protection, and a subject of decided value for nature study classes. Wasps. (Society for Visual Education.) Telling first the story of the changing of the grub to the wasp, and the mature wasp moistening the walled entrance to her cell and breaking her way out. ' Nest building by the wasp occupies the greater part of the reel. The mud-dauber brings the material from a nearby puddle and is shown in closeup as she builds. She rounds the entrance and smooths the inside using her jaws as a trowel. Good views show her cleaning the curled antennae after her strenuous labors. When the cell is completed she provisions it with spiders, on the last of which she lays one tiny egg and closes the entrance, after which she assumes no more responsibility but leaves the grub to take care of itself. Other varieties of wasps are shown, particularly the Polestes which builds a one-tier, horizontal comb in a protected nook. The queen attaches eggs to the sides of the cells, and the tiny grubs that hatch fit there snugly. When they are full grown, they spin silken nets over their nests and the change begins. Good views show the mature wasp emerging, thus completing the life cycle. Our Four-Footed Helpers. (Ruminants.) (Pathe.) Another of the Screen Sfudics, descriptive of the hoofed animals which are man's chief dependence for food, animal fibers and leather. The cow is perhaps the most familiar example, and the habit of cud-chewing, common to the group known as ruminants, is best illustrated in this case. A cross-section diagram with animated drawing, shows the various sections into which the stomach is divided. The non-digestive, or storage, stomach re