1911 Encyclopædia Britannica/Aestivation

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AESTIVATION (from Lat. aestivare, to spend the aestas, or summer; the word is sometimes spelled “estivation”), literally “summer residence,” a term used in zoology for the condition of torpor into which certain animals pass during the hottest season in hot and dry countries, contrasted with the similar winter condition known as hibernation (q.v.) In botany the word is used of the praefloration or folded arrangement of the petals in a flower before expansion in the summer, contrasted with “vernation” of leaves which unfold in the spring.