JAMAICA DOGWOOD. 107 



ing fish, and the bark of the root is the part used in medicine, and 

 should be gathered during inflorescence, otherwise it is unreliable. 



Description --Y\\& bark of commerce appears in pieces of two 

 to four inches in length, and from one to two inches wide, and 

 about an eighth of an inch in thickness. The outer surface of some 

 of the pieces is of a dark grey brown, while others are of a yellow 

 brown with no shade of grey present. The bark is frequently 

 studded with flattened protruberances of a lighter color than the 

 surrounding cork. 



The central part of the bark is much lighter colored, and when 

 wet or freshly broken is of a peculiar blue-green color. 



The inner part of the bark is of a dark brown color and very 

 fibrous. It has a strong, disagreeable odor of opium when broken 

 into pieces. It is strongly acrimonious and produces a burning sen- 

 sation in the mouth and pharynx. 



Microscopical Structure. The cork or outer bark (see fig. i, a) 

 is composed of about fifteen rows of thin-walled, regular, parenchy- 

 matous cells, brick shaped, and arranged radially, i. e., the length of 

 the cell standing parallel with the radius. They are generally 

 empty. 



The middle or green layer of the bark (b) is composed of thin- 

 walled, long, oval cells. In the longitudinal section they are 

 arranged tangentially, /. e., the longest diameter of the cell is at 

 right angles with the radius. They average about 1-250 of an inch 

 in length, and about one-fourth -as wide, containing clear white 

 chlorophyll bodies and dead protoplasm and chlorophyll. Occa- 

 sionally a crystal is found as if by accident. In the cross section 

 the cells are oval or round and of irregular sizes. Sometimes oil 

 cells are present. The cell walls themselves seem to have absorbed 

 coloring matter, for they are not a clear white as is usually the case 

 with cellulose. 



The inner layer of the bark or the liber layer (c) constitutes the 

 principal part of the bark, frequently being four-fifths of the whole 

 bark. It is composed principally of regular parenchymatous cells 

 of nearly equal diameters, and with thin walls. These cells are 

 quite regular toward the inner surface of the bark, and grow more 

 irregular toward the outer edge of this layer. Some of the cells 

 show pitted marks, which are deposits of cellulose on the cell walls. 



Bundles of liber fibre are arranged in concentric- rings through 



