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GROUP XX

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Originally appearing in Volume V21, Page 352 of the 1911 Encyclopedia Britannica.
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GROUP XX . See also:Digitalis.—This group-name has been given to a large number of substances which have an See also:action similar to that of the See also:foxglove leaves, including the active principles of See also:strophanthus, See also:squill, Urechites suberecta, Convallaria majalis, Nerium Oleander, Hellebores See also:niger, Antiaris toxicaria (the See also:upas See also:tree), and several others. The active principles of these vary a See also:good See also:deal in chemical See also:composition, but they are all non-nitrogenous neutral bodies. Their action is exerted upon muscle, and chiefly upon the muscle of the See also:heart and See also:blood vessels. The individual muscle-See also:fibres See also:con-See also:tract and expand more perfectly, and thus the diastole and systole of the heart are rendered more See also:complete, the See also:pulse is slowed, and the blood-pressure is raised. The slowing of the heart is partly brought about by an action on the vagus centre. Ggour XXI. See also:Picrotoxin.—In large doses the action of picrotoxin is exerted chiefly on the medullary See also:nerve centres, whereby irregular tonic-clonic See also:convulsions are produced; in See also:minute doses it stops the secretion of sweat.

End of Article: GROUP XX

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