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Join this channel to get access to perks: Want to learn more about Periscope Film and get access to exclusive swag? Join us on Patreon. Visit Visit our website This black-and-white educational film from 1966 demonstrates Charles Darwin’s pioneer experiments in the research of plants and their reaction to light, followed by botanists’ further experiments building upon Darwin’s results. The film is produced by Encyclopedia of Britannica Inc. in collaboration with educational advisor George I. Schwartz, M.S., Fellow at the New York Academy of Science. Stanley Croner is the executive producer of this film directed by Charles L. Finance, edited by Thea Bentler, and photographed by Frederic Goodich. “A Story of Discovery – Why Plants Bend Toward Light” title banner (00:23). Sprouted seeds in a petri dish (00:29). Individual sprouts are lined in a container (00:34). Footage of different animals in their forest habitat (00:52). A mallow weed plant bending towards the sun (01:24). An ivy vine (01:41). A houseplant stretching towards the light from a window (01:51). Charles Darwin, a pioneer in the research of why plants bend towards the light (02:01). A Darwin experiment using grass seedlings and a small gas lamp revealed that the sprouts bent toward the flame of the gas lamp (02:22). A tinfoil capped batch of grass seedlings revealed only the tip of the sprouts react to sunlight (03:26). The book “The Power of Movement in Plants” by Charles and Francis Darwin (04:11). The Danish botanist Peter Boysen Jensen, who continued Darwin’s research (04:42). His experiment involved cutting the tips off the sprouts (05:00). He then places a thin layer of gelatin on each stump and adds the cut-off tips on top of the gelatin (05:11), and then exposes the seedlings to light from one side (05:29). The experiment revealed that the sprouts bent toward the light confirming Darwin’s theory of a substance in only the top of the seedling (05:37). Thin mica plates are placed halfway through the cut between the tip and stump instead of gelatin (05:58). The Hungarian botanist Arpod Paul further developed the experiment by cutting off the tips of the seedings and replacing them in off-centered positions (06:41), and then he covered them to test their growth in darkness (07:08) revealing that all seedings bend due to the off-centered tips (07:17). The Dutch botanist Frits Went tested different types of lights’ effect on the plant (07:36). He cut off the tips and placed them in a block of agar to absorb the unidentified substance from the tips (07:49). He then cut the block of agar containing the absorbed substance into small squares and placed the pieces on the side of the seedlings (08:11). The result of the experiment revealed the squares containing the highest concentration of the substance led to the seedlings bending more (09:03). A mortar and pestle are used to grind leaves to a paste (10:00). Laboratory research on plant hormones and the extraction process (10:14). An airplane spraying a barley field with pesticide (10:38). A tomato blossom field is manually sprayed (10:59). A green house full of chrysanthemum plants are also sprayed manually with a chemical to slow the growth (11:07). A different chemical is added to corn seedlings to make them grow taller (11:20). A recap of the botanists, who performed the research and experiments (11:30). A plant tangling itself around a stem (11:40). A plant that reacts to touch (11:54). Carnivorous plants (12:02). We encourage viewers to add comments and, especially, to provide additional information about our videos by adding a comment! See something interesting? Tell people what it is and what they can see by writing something for example: “01:00:12:00 -- President Roosevelt is seen meeting with Winston Churchill at the Quebec Conference.“ This film is part of the Periscope Film LLC archive, one of the largest historic military, transportation, and aviation stock footage collections in the USA. Entirely film backed, this material is available for licensing in 24p HD, 2k and 4k. For more information visit
