SECTION XI 



DRIED JUICES 



A number of plants exude on incision liquids that have been 

 contained in certain specialised cells. These liquids differ in their 

 composition from the latex contained in laticiferous tissue and also 

 from the oil, oleo-resin, or oleo-resinous emulsions secreted in cells, 

 glands, or ducts. Some of them contain substances of medicinal 

 value, as, for instance, various species of Aloe, Eucalyptus, &c. ; 

 these yield when dried drugs that, for want of a better term, have 

 been designated ' dried juices.' In many cases tannin forms the chief 

 constituent as it does in the various kinos ; in others, particular 

 substances not produced in other natural orders or even genera are 

 found, such as aloin. 



ALOES 



(Aloe) 



Source, &C. Aloes is officially described as the juice that flows 

 from the transversely cut leaves of certain species of Aloe (N.O. 

 Liliacece) evaporated to dryness. 



The aloe plants are indigenous to eastern and southern Africa, 

 but have been introduced into other tropical countries, as for instance 

 the West Indies, and will flourish even in southern Europe. They 

 produce spikes of yellow or red flowers and large fleshy leaves resem- 

 bling those of the American agave, an ornamental plant commonly 

 grown in this country and often erroneously called an aloe. 



The leaf which is fleshy and mucilaginous in its interior, contains 

 near the epidermis a row of isolated fibrovascular bundles each of 

 which is surrounded by an endodermis. The cells of the pericycle 

 and sometimes of the neighbouring parenchyma are unusually large, 

 and filled with a viscous, yellow liquid, the aloetic juice. When the 

 leaves are cut from the plant this juice slowly drains from the cells 

 containing it. Probably the transverse walls of the elongated and 

 axially arranged cells give way under the pressure exerted upon 



