THE JOURNAIv OF PHARMACOLOGY. 47 



holes that are about as broad as the kimen, then the fibers are probably 

 derived from firs (Fahrenholz, Fig. 36). 



With reference to the differences found in the fibers of the principal 

 foliage trees that are used in the fabrication of paper, they are succinctly 

 as follows : 



The wood elements of the willow, the aspen and the linden are 

 very thin-walled ; those of maple (hard maples) are thicker walled ; 

 if the red maple is used, the fibers are thin-walled. The wood of linden 

 shows portions of vessels and tracheids which possess in addition to bor- 

 dered pores also a broad spiral band. The vessels measure up to 60 

 mikra in width. Maple wood also sometimes has vessel portions provided 

 with bordered pores and spiral markings, but usually either the bordered 

 pores or the spiral bands alone are present. Willow and aspen have 

 similar wood with ducts that are entirely covered with six-sided bor- 

 dered pores. 



Paper or paper-material (Papierstofif) containing wood-fibers always 

 gives the lignin-reactions very distinctly. For instance aniline sulphate 

 gives a golden yellow coloration, etc. 



It is to be noted that there are wood-pulps, but no papers, that are 

 made up entirelj' of wood-fibers. Therefore, in papers in \vhich lignin 

 (holzstoflf) has been detected one must also search for other fibers which 

 can be distinctly seen after the lignin tests have been applied. 



II. JVood Cellulose. — When wood is acted upon by chemical means (dil- 

 caustic soda under high pressure, etc.) and thus decomposed into its com- 

 ponent parts, we obtain a substance called cellulose or wood-cellulose. 



Whereas wood-fibers respond strikingly to the lignin tests, paper con- 

 taining cellulose reacts but very feebly or not at all. 



Not alone does the lignin become destroyed in the macerating process, 

 but many of the characters of the wood elements become altered, so that 

 under the microscope wood-cellulose is not as readily recognized as are 

 wood- fibers. 



Wood cellulose, it appears, is prepared usually from the long-fibered 

 evergreens. The fibers appear broad, ribbon-like, twisted in many places 

 and often resemble cotton fibers (but broader); thin-walled ; here and 

 there may be seen large bordered pores, but always indistinctly. 



They are best brought to view by treating the fibers with zinc chloro- 

 iodide, whereby the majority take on a violet color, others a dirty violet 

 to yellow coloration. 



The fibers are 30 mikra to over 60 mikra in diameter and show no dis- 

 locations. They are also but little torn, whereas wood-fibers are much 

 tattered and torn. The ends are mostly broad, thin-walled, blunt and 

 rounded off. But few medullary ray elements are to be found, and they 

 show only indistinct structural characters. 



