CONVOLVULACE^E. 477 



sant odour, and a bitter and acrid taste. In drying, the root loses about three- 

 fourths its weight. As found in the shops, it is usually in circular pieces of 

 various sizes, being transverse sections, the colour somewhat brown exter- 

 nally and whitish within, with radiating stria?. They are powdered with 

 difficulty, the powder is light and gray. According to an analysis by Mr. 

 Shinn (Am. Journ. Pharm. v. 177), this root contains Resin, Bitter extractive, 

 Starch, Gum, Gallic acid, &c. 



Medical Properties. — The real qualities of this article are not well ascer- 

 tained. Dr. B. S. Barton (Collections), says he knows nothing of it from ex- 

 perience ; but that an extract but little inferior to scammony has been procured 

 from one of the native species of Convolvulus, and further states that it was 

 used with great success by Dr. Harris, of New Jersey, in calculous com- 

 plaints, and also that it had obtained some celebrity in Virginia in the same 

 disease; it was generally given in decoction. It has also a reputation among 

 empirics, and in domestic practice, as a substitute for rhubarb and jalap, but 

 is much feebler in its action than either, as it requires large doses to produce 

 any effect. Elliott observes, that it certainly possesses some cathartic power, 

 but in too slight a degree to bring it into use. The extract may perhaps be 

 found useful, but certainly can never be equal to scammony. The dose of 

 the powder is forty grains to a drachm. 



Another species of this genus, the I. turpethum, a native of several parts 

 of Asia, was at one time in very general use as a purgative, but is now sel- 

 dom employed, although it certainly possesses active properties; according to 

 Ainslie, it is much esteemed by the native practitioners in India, and even in 

 Europe it is spoken of in high terms by some writers, but is never prescribed 

 in this country. The I. pes caprce, corymbosa, discolor, and many others, 

 have likewise been employed in different countries. A purgative resin is also 

 obtained from I. tuber osa ; and it is stated by Mr. Hartweg that what is called 

 Male Jalap is -the product of the /. batatoides (Lindley, Veg. King, 631). I. 

 operculata yields a purgative drug called Gomma da Batata, which is said 

 to be equal to Jalap (Gomez, Obs. Bot. Med. 23). I. cathartica has also a 

 purgative root, employed as a cathartic in St. Domingo; it is said to often 

 cause superpurgation. 



Lindley is of opinion that I. oririzabensis is the " Jalapa macho," or male 

 Jalap of Mexico, specimens of which were sent to France by M. Ledannois, 

 and described by M. Pelletan in the Journ. Chim. Med. x. 1. It is the I. 

 mestilantica (Choisy) ; and M. Ledannois states that the roots are a good pur- 

 gative, without possessing the acridity of the common Jalap, and that he 

 always administered them with success (Journ. Phil. Coll. Pharm. iii. 265). 

 Lindley further states that Dr. Schiede had seen the roots, and found them to 

 be very like that of I. purga (Flor. Med. 397). 



Convolvulus. — Linn. 



Sepals 5. Corolla campanulate. Style 1 ; stigmas 2 ; linear-cylindrical, often revo- 

 lute. Ovary 2-celled, with 4 ovules. Capsule 2-celled. 



Almost as extensive a genus as lpomsea, and resembling it in many 

 respects in its botanical as well as its physical characters. 



C. scammonia, Linn. — Stem smooth ; leaves sagittate, posteriorly truncate ; lobes entire 

 or elongate-laciniate ; peduncles very long, many-flowered. 



Linn., Sp. PI. 218; Woodville, ii. 243; Stokes, i. 322; Stephenson and 

 Churchill, i. 60 ; Lindley, Flor. Med. 398. 



