1898.] MIOHOSCOPICAL JOUENAL. 171 



minutely wrinkled, and the margin crenulate. The leaf 

 is furnished with oil cells in exactly the same way as B. 

 hetulina. The odor recalls that of horsemint {Mentha 

 aquatica), and the flavor that of peppermint, with a 

 trace of carraway. 



B. SERRATIFOLIA. — The leaves are linear-lanceolate, 

 varying from 1 to li inch in length, and from i-i inch in 

 width in the middle (fig. C and c). They are obtuse at 

 the apex and serrulate at the margins, glabrous, polished, 

 and minutely wrinkled, and are furnished with oil-cells in 

 the same manner as the two preceeding species. The 

 odor and flavor resemble those of B. crenulata, but the 

 taste is more distinctly bitter. Buchu apparently owes 

 its properties to an essential oil. In the case of B. 



' betulina the oil affords a crystalline deposit of diosphenol 

 which has been ascertained by Dr. Cash to possess anti- 

 septic properties. It has an odor like menthol. The 

 leaves also yield a ketone resembling menthone, and a 

 hydrocarbon. The leaves in addition yield mucilage and 



j, contain hesperidiu. 



The epidermis consists of tabular polyhedral cells (five 

 to six sided), without stomata on the upper surface of 

 the leaf. These cells contain amorphous masses or 

 sphserocrystals of hesperidin (see figure). Between the 

 epidermal layer and the palisade cells there is a layer oi 

 colorless cells, thin and with irregular walls, as seen in 

 alcohol or almond oil, but in water swelling up and form- 

 ing mucilage by the dissolution of the walls (see figure). 

 The mesophyll consists of a single layer of palisade cells 

 and a spongy parenchyma beneath, sphseraphides occur- 

 ing in some of the cells. The oil cavities are lined with 

 two or three layers of flattened cells. Those at the base 

 of the marginal teeth occupy nearly the whole thickness 

 of the leaf. The lower epidermis is furnished with 

 stomata. The midrib is not prominent on the upper sur- 

 face, and very slightly so below. It consists of a woody 



