702 A TEXT-BOOK OF BOTANY. 



YOHIMBI (Yohimbihi) bark is obtained from Corynanthe Yo- 

 himbe, a tree growing in the Cameroon region of Africa. The 

 pieces of bark are 25 cm. or more in length, 5 to 8 mm. thick, 

 externally dark brown or grayish-brown, and somewhat bitter. 

 Numerous bast fibers are present, but no sclerotic cells. It yields 

 4 alkaloids (0.3 to 1.5 per cent.), the principal one being yohim- 

 bine (corymbine or corynine), which forms white prismatic 



FIG. 390. Picking coffee in Brazil. The coffee shrub is cultivated in plantations, and 

 when the berries are ripe they are collected either by shaking the tree and allowing the 

 berries to fall upon a cloth or they are picked by hand directly from the branches, and 

 removed from the field by oxen teams. More than half of the coffee of the world is grown in 

 Brazil, the remainder being obtained in various parts of tropical America and East India. 

 Reproduced by permission of The Philadelphia Commercial Museum. 



needles, soluble in alcohol and almost insoluble in water, and on 

 treatment with nitric acid becomes first deep green and then 

 yellowish, changing to a cherry-red if followed with an alcoholic 

 solution of potassium hydroxide (distinction from cocaine). 



A number of the Rubiaceae contain valuable coloring prin- 

 ciples, as the madder plant (Rubia tinctorum}, which is a peren- 

 nial herb occurring wild in Southern Europe and formerly culti- 

 vated in France and Germany on account of the coloring principle 



