The root cap is a special layer of tissue which protects the tip of a growing root and helps to anchor the plant. At the very tip of the root is a loose mass of parenchyma cells which continually slough off and regenerate with the growth of the root system. In addition to protecting the interior of the root, the cap secretes a mucilage which stabilizes water content of the surrounding soil, ensuring longer-lasting nutrition to the root system and making for easier root probing. Finally, the root cap contains statocytes, which are specialized cells that help the plant to sense gravity and grow accordingly. These cells are full of starchy organelles which settle at the lowest part of the cell and encourage growth in that direction. If the root cap, with these statocytes, is removed, plants may grow in random directions because it has lost the ability for gravitropism.
Does anybody know the etymology of the phrase "sweet dreams"? I tried googling but did not find anything satisfying. Is this a relatively new phrase of the modern world or has this been in use for some time? I think it's the latter one. Answer The OED has the interjection as "a farewell to someone going to bed" from the 20th century: 1908 Sears Roebuck Catal. 198/1 Tenor Solos..Good Bye, Sweet Dreams, Good Bye. But it goes back until at least the 19th and possibly 18th centuries. John Wolcot, writing under the pseudonym of Peter Pindar, used it in his poem "Orson and Ellen; A Legendary Tale" published in 1801: Also from 1801 in The infernal Quixote (Page 287) by Charles Lucas: In the March 1776 of The Universal Magazine was published "The Serenade. A Pastoral Tale. From the German of Gesner" , where the shepherd Daphnis watches over his beloved as she sleeps and sings: The same tale appears in 1776's as Idyl XI, " Daphnis ...
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