CLASS XT, ORDER II.] SI. V APIS. 919 



sinapin and volatile oil, it is rendered most active when mixed with 

 vinegar and warm water, and not spirits of wine or brandy, as these 

 prevent the formation of the volatile oil. The seeds of the White 

 Mustard have been considered a valuable stimulating cathartic ; and in 

 some cases when the bowels are weak and require a stimulating 

 aperient, one or two table spoonsful of the seeds, swallowed whole 

 early iu the morning, have been found useful. From what we have 

 above stated of the properties of these seeds, it will be seen that their 

 action depends upon the presence of the sinapin, and that as the 

 seeds pass along the alimentary canal, they absorb moisture ; and this, 

 combining with the sinapin, forms the stimulating volatile oil, which 

 is gradually evolved, but rendered milder by its admixture with the 

 oil and mucilage, &c. of the other parts of the seed. This mode of 

 taking the seeds, however, is not without great objections, and cases 

 have been reported where from their lodgment in the bowels they have 

 produced inflammation, ulceration of the intestines, and death, and as 

 many other equally good and unobjectionable medicines are known 

 having the same properties, the Mustard seeds in this form are justly 

 neglected. 



3. S. ni'gra, Linn. (Fig. 1061.) Common Mustard. Siliqua smooth, 

 quadrangular ; style short, quadrangular, erect, close pressed to the 

 stem ; the lower leaves rough, lyrate, and toothed, the upper linear, 

 lanceolate, entire, smooth. 



English Botany, t. 969. English Flora, vol. iii p. 222. Hooker, 

 British Flora, ed. 4. vol. i. p. 2o6. Lindley, Synopsis, p. 33. 



Soot small, tapering. Stem erect, from three to four feet high, 

 round, smooth, branched and leafy, the lower leaves large, lyrate, 

 lobed or sinuated, toothed, rough, with short rigid hairs, the upper 

 ones linear, lanceolate, spreading or drooping, petiolated, smooth, 

 entire. Inflorescence terminal and lateral sub-corymbose racemes of 

 bright yellow flowers, much elongated after flowering. Calyx of four 

 oblong yellowish pieces, widely spreading. Petals roundish, ovate, 

 tapering into a claw. Stamens as long as the calyx. Fruit a small 

 obtusely quadrangular siliqua, smooth, and nearly even, crowned by 

 the short quadrangular style, and obtuse stigma. Seeds not very 

 numerous, yellowish brown, globose. 



Habitat. Waste places, road sides, &c. 



Annual; flowering in June. 



The seeds of this species possess similar properties to the last, but 

 are more acrid and pungent in its flavour, and contain less of the 

 fixed oil. 



4. S. inca'na, Linn. (Fig. 1062 ) Hoary Mustard. " Pods ap- 

 pressed, turgid, with a short one seeded beak ; leaves lyrate, hispid, 

 cauline ones linear, lanceolate ; stem much branched." 



