99 



EXOGOXIUM PORQA, Benth ; IPOMOJA POEGA, Hayne. (Vera Cruz 

 Jalap.) 



a. Boot, etc., preserved wet. J). <t T., Mud. Plant*, tab. 186. 

 Note. This specimen was grown at Clapham, and was presented by 



Mr. D. Hanbury. It shows the formation of tnbercules by the enlargement 

 of roots proceeding from a slender subterranean stem. 



b. Tabercules, preserved wet. 



Note. This specimen was grown in the Botanical Garden of Trinity 

 College, Dublin, and was presented by Dr. Aquila Smith, in May, 1869. 



c. Tubercules. Two specimens. 



d. Resin obtained from the tubercules. (Jalapin.) 



e. Ditto, purified. 



t /. Large pyrifonn jalap tubercules. 



t g. One large globular ditto. 



Note. True Jalap is distinguished from Tampico by being usually 

 turnip-shaped or pear-shaped, by its density, by not being shrunken, and by 

 being marked with numerous little transverse scars, which are absent 

 in Tampico Jalap. For culture of, see P. J. [2] , TO!, viii., p. 651. For 

 valuation of, P. J. [2], vol. ix., p. 487. For resin, P. J. [1], vol. iv., 

 p. 428 ; [2] , vol. ix., p. 233. For adulteration of jalap resin, P. J. [1] , 

 vol. iii., p. 132 ; [2] , vol. iv., p. 326. The root contains 15 per cent, of 

 resin, about 5 per cent, of which is soluble in ether, the rest insoluble. 



393. IPOM(EA ORIZABENSIS, Ledan. 



a. Root. (Male or Stalk Jalap, Woody Jalap, Orizaba Root, 



Purgo macho of the Mexicans.) 



Note. This root contains a resin entirely soluble in ether. See P. J. 

 [1] , vol. iii., p. 133 ; [1] , vol. xi., p. 521, No. 1 ; [1] , vol. iv., p. 326. 



394. IPOM<EA SPECIES. 



a. Tubercules. (Jalap with a roseate odour.) 

 Note. This Jalap much resembles in appearance Tampico Jalap, but 

 occurs in much larger pieces. It was found by Guibourt in French 

 commerce in 1842, and was presented by him. It contains according to 

 his analysis only 3'23 per cent, of resin, about half of which is insoluble 

 in ether. The roseate odour is not now (1875) perceptible. P. J. [1], 

 vol. ii., p. 331. 



395. JpOM(EA SIMULANS, Hanbury. 



a. Tubercules. (Tampico Jalap.) 



Note. The Tampico Jalap plant was first described by Mr. D. Hanbury, 

 and is figured in the Journ. Linn. Soc., vol. xi. (1870), 279, tab. 2. See 

 also P. J. [2] , vol. xi., p. 848. It is distinguished from the true Jalap 

 plant by its corolla being funnel-shaped, and its flower-buds drooping ; 

 the corolla of Exogonium purga is spread out horizontally like a wheel, 

 and the flower-buds are erect. The tubercules are paler, more spongy, and 

 are fusiform in shape. They yield a resin entirely soluble in ether. 

 As imported, the drug often appears to be mixed with true Jalap, which 

 will perhaps account for the different opinions held concerning the solu- 

 bility of its resin in ether. Pharmacographia, p. 402. The tnbercules 

 have been mistaken for the roots of Nepaul Aconite. See Aconitum ferox, 

 and P. J. [2] , vol. vii., p. 58. 



