76 COMMERCIAL BOTANY. 



roots seems to be as necessary as good culture of the plants. 

 In the report of the Jamaica experiment it is said that "the 

 application of too much heat was apt to change 'the 

 character of the starch grains and convert them into an 

 amorphous mass.' The small tubers were dried whole, 

 while the larger ones were sliced or gashed." These latter 

 were not approved of in the London market, while in New 

 York they fetched higher prices than with us, and no 

 objection was made to the slicing. 



Jalap is imported chiefly from Vera Cruz, and is brought 

 into the United Kingdom to the extent annually of 180,000 

 pounds. 



RHUBARB (Rheum offidnale). This fine species was dis- 

 covered in South-eastern Thibet, where it is said to be often 

 cultivated for the sake of its root for use in medicine. The 

 plant was first obtained about 1 867. It was first grown in 

 this country in 1873 by the eminent pharmacologist, Daniel 

 Hanbury ; after which it was cultivated for medicinal 

 purposes at Bodicote near Banbury, where it is still grown. 

 At one time it was supposed to be the source of the best 

 quality of medicinal rhubarb; more recent information, 

 however, has shown that this is the produce of Rheum 

 palmalum, a large perennial herb first found wild by 

 Colonel Prejavalsky in 1872-3 in the Tangut district of 

 Kansu. It is said to extend over a large tract of country, 

 but not to be cultivated, though sometimes grown as a 

 garden plant. It is this species that is now known as the 

 real source of the Russian or Turkey rhubarb of commerce, 

 and is derived alone from the provinces of Shensi, Kansu, 

 and Szechuen. So great is the demand for medicinal 

 rhubarb at the present time that as many as 625,000 pounds 

 are annually sent from Hankow to Shanghai, 350,000 

 pounds of which find their way into the United Kingdom. 



SOCOTRA ALOES (Aloe Perryi). The discovery of the 

 source of true Socotrine aloes is one of considerable interest 



