474 VEGETABLE DRUGS 



duced by cathartics, and disguise and offset disagreeable 

 effects and tastes of medicines. In the digestive tract, vola~ 

 tile oils excite reflexlj the nervous system and heart, and 

 augment the pulse rate and vascular tension. In large doses,, 

 volatile oils are gastro-intestinal irritants. Volatile oils may 

 be absorbed from the skin, bronchial mucous membrane, and 

 stomach. They are eliminated by the skin, bronchial mucous 

 membrane, and kidneys, and occasionally by other channels. 

 In the process of excretion the parts are stimulated, vascu- 

 larity, secretion, and contractility of the unstriated muscle 

 of the bronchial tubes are increased, and volatile oils thus 

 assist expectoration and coughing. In irritating the kidneys 

 and mucous membrane of the genito- urinary tract, the vola- 

 tile oils are stimulant and diuretic ; while in poisonous doses 

 they produce acute nephritis, strangury, and haematuria. 

 Toxic doses, injected into the circulation, lower the force of 

 the heart and the blood pressure, and occasion a sort of 

 intoxication, and sometimes convulsions. To summarize r 

 volatile oils possess the following actions in a greater or less 

 degree : parasiticide, antiseptic, disinfectant, rubefacient, 

 vesicant, local anaesthetic, sialogogue, stomachic, carminative,^ 

 antispasmodic, stimulant, expectorant, emmenagogue, and 

 diuretic actions. 



Class 1. — Used Mainly for their Action on the Skin. 



Terebinthina. Turpentine. (U. S. & B. P.) 



A concrete oleoresin obtained from Pinus palustris^ 

 Miller, and from other species of Pinus (nat. ord. ConifersB). 



Habitat. — Southeastern United States ; from Virginia to 

 the Gulf of Mexico. 



Description. — In yellowish, opaque, tough masses, brittle 

 in the cold ; crumbly, crystalline in the interior, of a terebin- 

 thinate odor and taste. 



Oleum Terebinthina. Oil of Turpentine. 

 A volatile oil distilled from turpentine. 



