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THE JOURNAL OF PHARMACOLOGY. 



The xylem is seen to be 

 principally composed of 

 distinctly marked libriform 

 fibers. These markings are 

 the small, round or slit- 

 shaped pores, which are 

 distributed throughout the 

 length of the fiber. The 

 tracheids are distinguished 

 by their larger diameter and 

 thinner walls. Their mark- 

 ings are in part similar to 

 those of the wood fibers, 

 but more pronounced oval 

 pores are common. 



The ducts are of two 

 kinds, the reticulated and 

 spiral. The former are dis- 

 tributed throughout the en- 

 tire woody portion of the 

 bundle. They are from two 

 to four times the diameter 

 of the wood fibers. The ir- 

 regular, angular pores are 

 so numerous as to leave 

 merely a net of the cell 

 wall. The spiral ducts oc- 

 cupy exclusively the inner- 

 most portion of the xylem. 

 Both single and double 

 spirals are present. The parenchyma is now reached. Its outermost 

 cells are seen to be long and narrow, with many pores. The inner cells 

 gradually become shorter and broader until at the center ; the longest are 

 not over twice as long as broad. They are far more irregular than is ap- 

 parent on cross-sections, and many cells are seen with a diameter greater 

 than their length. 



Fig. 4 represents the appearance of the powder. In addition to the 

 elements of the stem above described, it contains the elements of the leaf 

 and flower. 



The following may be defined : 

 From the stem : 

 (i) Bast fibers ; 

 (2) Ducts ; 



Fig. 



