352 SUBTERRANEAN ORGANS 



the eastern slopes of the Mexican Andes. It sends out slender runners 

 which are provided at intervals with scaly, cataphyllary leaves in the 

 axils of which are buds ; below the buds roots are produced, some of 

 which thicken rapidly and form fusiform or napiform organs, often of 

 considerable size. These tuberous roots (tubercules) are collected 

 and dried in nets over fires, the smaller entire, but the larger longi- 

 tudinally incised to allow of the free escape of moisture. When fresh 

 they are fleshy and white internally, but by drying, especially in the 

 manner indicated, they darken in colour. Jalap is imported in sacks 

 from the east coast of Mexico, and distinguished as ' Mexican ' or ' Vera 

 Cruz ' jalap. 



The jalap plant has been cultivated in India and Jamaica but these 

 colonies do not at present compete with Mexico in the supply of thedrug. 



The Spaniards became acquainted with this and similar purgative 

 Convolvulaceous plants early in the sixteenth century, and exported 

 considerable quantities of them to Europe. 



Description. Jalap occurs in pieces of very varying size, most 

 commonly about that of a hen's egg, although sometimes they attain 

 10 cm. or more in diameter. They vary also much in shape, being 

 sometimes napiform, sometimes fusiform or irregularly oblong. The 

 small are usually entire, but the larger bear gashes that have been 

 made to facilitate the drying. Towards the lower extremity they 

 taper off and show a fractured end where the slender part of the root 

 has been broken off. The surface is dark brown, furrowed and wrinkled 

 (but not conspicuously convoluted), and marked with numerous, 

 paler, elongated transverse scars (lenticels). They are heavy and 

 compact, and so hard as to be broken with difficulty, but softening 

 readily in water. Internally they have a yellowish grey or dingy grey 

 colour, and are very tough or horny, the section exhibiting irregular 

 dark lines often concentrically arranged. These lines are due to the 

 formation of secondary cambiums, an abnormal development that is 

 occasionally, although not often, met with. Under the lens numerous 

 dark resin cells are visible, especially in the cortical portion, but woody 

 tissue is not easily discerned. 



Jalap has a distinct and characteristic odour which is often ascribed 

 to the smoke from the fire over which the roots have been dried, but 

 which is, partly at least, inherent in the drug. The taste is at first 

 sweetish, but afterwards disagreeably acrid. 



The heat to which the drug is subjected during the drying is generally 

 sufficiently high to gelatinise the starch, especially in the interior of 

 the roots, where the moisture is retained longer than in the outer 

 portions ; hence the horny and not starchy appearance of the drug. 

 Roots obtained from cultivated plants in India and Jamaica are usually 

 more carefully dried, and present a mealy, not horny, appearance in 

 the interior. 



