WHITE HOREHOUND 207 



The student should observe 



(a) The dense felted hairs on the stem and leaves, 

 (6) The ten hooked teeth of the calyx. 



Constituents. White horehound contains a bitter principle, mar- 

 rubiin (0'25 per cent.), crystallising in colourless plates melting 

 at 154 ; it is almost insoluble in water, but soluble in alcohol and 

 ether ; a little volatile oil and tannin are also present. 



Uses. Horehound has tonic, stimulant, and expectorant properties ; 

 it is used as a domestic remedy for coughs and pulmonary complaints 

 generally. 



Substitutes. The following plants have been substituted for M. 

 vulgare : 



M . peregrinum, Linne ; has ten straight calyx teeth. 



M . candidissimum, Linne, has five nearly straight calyx teeth ; is 

 less aromatic and less bitter. 



Ballota nigra, Linne (black horehound) ; is dark green ; hairs rough, 

 not woolly ; five broadly ovate, pointed calyx teeth. 



B. hirsuta, Bentham ; calyx funnel-shaped, densely hairy, with ten 

 broadly acute or mucronate teeth, 



INDIAN HEMP 



(Cannabis Indica) 



Source, &C. The drug known as Indian hemp, or Cannabis indica, 

 is derived from Cannabis sativa, Linne (N.O. Urticacece), cultivated 

 in tropical districts of India. 



The plant is an annual dioecious herb, indigenous to Central and 

 Western Asia, but largely cultivated in temperate countries for its 

 strong fibres (hemp) and its oily seed (hempseed), and in tropical 

 countries also for the resinous secretion which it there produces. 

 This secretion possesses powerful medicinal properties, but it is not 

 produced by the plant when grown in temperate climates ; on the 

 other hand, the fibre of the plant under the latter condition is stronger 

 than that of the tropical plant. 



The cultivation of hemp for its seed and fibre dates from very remote 

 periods. It was used as an intoxicant by the Persians and Arabians 

 in the eleventh and twelfth centuries, and probably much earlier, but 

 was not introduced into European medicine till comparatively recently 

 (1838). It is -largely grown in the districts to the north of Calcutta, 

 and westward thence through Central India to Gujerat. Very good 

 qualities of the drug are produced in Madras. 



As the staminate plants produce but little resin they are eradicated 

 and the pistillate plants pruned in order to produce flowering branches. 



