CLASSIFICATION OF ANGIOSPERMS. 381 



annually in the latter country. The yield of one tree is between 

 I and 12 pounds. There are two methods of freeing the seeds 

 from the parchment-like endocarp: In the one case the fruits 

 are allowed to dry and are then broken ; in the other case, which 

 is known as the wet method, the sarcocarp is removed by means 

 of a machine, and the two seeds with the parchment-like endocarp 

 are allowed to dry in such a manner as to undergo a fermentation, 

 and after drying the endocarp is removed. Cofifee seeds contain 

 from I to 2 per cent, of caffeine ; from 3 to 5 per cent, of tannin ; 

 about 15 per cent, of glucose and dextrin ; 10 to 13 per cent, of a 

 fatty oil consisting chiefly of olein and palmitin ; 10 to 13 per 

 cent, of proteins ; and yield 4 to 7 per cent, of ash. The official 

 caffeine is derived in part from coffee seeds. 



In the ROASTING of coffee there is a change in the physical 

 character of the seeds, as well as a change in some of the constit- 

 uents. The AROMA is supposed to be due to an oil known as 

 coffeol, which is said to be a methyl ether of saligenin. 



YoHiMBi (Yohimbihi) bark is obtained from Corynanthe Yo- 

 himbi, 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 

 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 Rubiacese contain valuable coloring prin- 

 ciples, as the madder plant (Rubia tinctoriim) , 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 

 in its roots. The root is known commercially as madder, and con- 

 tains when fresh a yellow coloring principle, which on the drying 

 of the root breaks up into several glucosides, one of which on 

 further decomposition yields alizarin, the principle to which the 

 red color of the dried root is due. At present alizarin is made 

 artificially from anthracene, a coal-tar derivative. 



Morinda citrifolia, a shrub widely distributed in tropical coun- 



