432 



DRIED JUICES 



*& 



them by the surrounding tissue, and thus the aloetic juice is drained 

 from cells situated at a considerable distance from the incision. 



Little or nothing flows from the mucilaginous tissue in the centre 

 of the leaf, and as it contains no aloetic juice no effort is or should 



be made to obtain it ; in 

 fact, its presence would 

 lower the quality of the 

 aloes. 



The drug is obtained 

 chiefly from Eastern and 

 Southern Africa and from 

 the West Indies. The 

 means by which it is pre- 

 pared are probably prac- 

 tically identical in all three 

 countries. The leaves are 

 cut from the plant and 

 placed so that the juice 

 that drains from the aloe- 

 tic cells may be received 

 in any convenient vessel. 

 This juice is then concen- 

 trated, either (probably) 

 by allowing it to evaporate 

 spontaneously (Socotrine 

 aloes) or by boiling it until 

 it has reached the desired 

 consistence, when it is 

 poured into boxes or 

 gourds (West Indian aloes) 

 or transferred it to kegs 

 (Socotrine aloes) or skins 

 (Zanzibar aloes), or cases 

 or barrels (Cape aloes) and 

 allowed to solidify. 



The manner in which 

 this operation is performed 

 has a remarkable influence 



on the physical characters of the aloes. If the juice is rapidly 

 concentrated, the concentration carried as far as practicable, and 

 the resulting aloes quickly cooled, a drug is obtained that breaks 

 with a vitreous or glassy fracture, and in small splinters is quite 

 homogeneous and transparent even when examined under the 

 microscope. Such an aloes is termed a * vitreous,' ' lucid,' or ' glassy ' 

 aloes. But if the evaporation is carried on slowly and not quite so 

 far as in the preceding case, a drug is obtained that is opaque and 



FIG. 239. Transverse section near the margin 

 of an Aloe leaf, ep, epidermis ; gfb, vas- 

 cular bundle, the pericyclic cells, a, of 

 which are much enlarged and contain a 

 yellow secretion (aloes) ; p, palisade ; g, 

 parenchyma ; sp, stoma ; cr, calcium oxa- 

 late crystals; m, mucilaginous paren- 

 chyma. (Magnified.) (Tschirch.) 



