BUCHU. 203 



Powder. — In the fresh state the powder is light green. 

 The characteristic elements found are: Epidermal cells, 

 stomata, crystals, fibres, parenchyma, cork cells. The 

 epidermis cells are small, irregularly polygonal, thick- 

 walled. The stomata are broadly oval, present in both 

 epidermal surfaces, superficial. Strongly lignified fibres 

 are present in large numbers, and vessel elements are 

 more prominent in eucalyptus leaves than is usual in 

 other leaves. Both rosette and rhomboid crystals are 

 present in considerable quantities. Collenchyma cells 

 are abundant, and occasionally cork cells are found. 

 These are derived from peculiar lenticels, or wounds, at 

 times found on the leaves. 



Chemistry. — The principal constituent of eucalyptus 

 is the volatile oil. This is colorless or slightly yellow, 

 boiling at 1 70° C, specific gravity 91 5 to 925, soluble in all 

 proportions of alcohol or glacial acetic acid. It consists 

 principally of eucalyptol (about 70 per cent.) ; eucalypten 

 and eucalyptolen are also present. The leaves contain 

 also galli'c and tannic acid, eery lie alcohol, pyrocatechin, 

 and a crystallizable acid fusing at 247° C. 



BUCHU. 



** The leaves of Barosma betnlina (Thunberg), Bartling 

 et Wendland, and Barosma crenulata (Linn^), Hooker 

 (nat. ord. Rutacece).*' 



Both plants are slender shrubs, about i m. high, grow- 

 ing in Southern Africa, in the districts of Clanwilliam 

 and Worcester, north and northeast of Cape Town. 



Description. — The leaves of Barosma hetulina are 10 to 

 20 mm. long, obovate or almost round, cuneiform at the 

 base, ending in a recurved point, margins serrate, with 

 numerous oil-glands, one in each serration, which render 

 the leaf pellucid punctate. The leaves are thicker than 

 those of the other varieties. 



The leaves of Barosma crenulata are oblong, oval or 



