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tissue culture

(Encyclopedia)tissue culture, the propagation of plants through the placement of small amounts of undifferentiated tissue or single cells in an artificial environment. The tissue is placed in a nutrient medium that...

Theocritus

(Encyclopedia)Theocritus thēŏkˈrĭtəs [key], fl. c.270 b.c., Hellenistic Greek poet, b. Syracuse. The history of the pastoral begins with him, and in him the form seems to have reached its height. His poetic st...

National Aeronautics and Space Administration

(Encyclopedia)National Aeronautics and Space Administration (NASA), civilian agency of the U.S. federal government with the mission of conducting research and developing operational programs in the areas of space e...

dog racing

(Encyclopedia)dog racing, trials of speed between dogs. Now contested on oval tracks, the sport developed from the ancient practice of coursing, in which specially trained dogs chase game animals in the open field....

cyclamate

(Encyclopedia)cyclamate sīˌkləmātˌ, –mət [key], any member of a group of salts of cyclamic acid (cyclohexanesulfamic acid). The sodium and calcium salts were commonly used as artificial sweeteners until 196...

Hyde Park, park, London, England

(Encyclopedia)Hyde Park, 615 acres (249 hectares) in Westminster borough, London, England. Once the manor of Hyde, a part of the old Westminster Abbey property, it became a deer park under Henry VIII. Races were he...

Paré, Ambroise

(Encyclopedia)Paré, Ambroise äNbrwäzˈ pärāˈ [key], c.1510–1590, French surgeon. Serving in the army, he revived the use of ligature instead of cautery with boiling oil and continued to devise and champion ...

fertilizer

(Encyclopedia)fertilizer, organic or inorganic material containing one or more of the nutrients—mainly nitrogen, phosphorus, and potassium, and other essential elements required for plant growth. Added to the soi...

parthenogenesis

(Encyclopedia)parthenogenesis pärˌthənōjĕnˈəsĭs [key] [Gr.,=virgin birth], in biology, a form of reproduction in which the ovum develops into a new individual without fertilization. Natural parthenogenesis ...

carbonated beverage

(Encyclopedia)carbonated beverage, an effervescent drink that releases carbon dioxide under conditions of normal atmospheric pressure. Carbonation may occur naturally in spring water that has absorbed carbon dioxid...