50 THE JOURNAIv OF PHARMACOLOGY. 



pally of a clay and resin soap with some (1-2 per cent, of the weight of the 

 paper) starch. 



In England, however, animal glue is chiefly used, though occasionally 

 a soap made of clay and wax is also employed. 



The above-mentioned clay and resin soap may be recognized by the 

 presence of starch granules. Animal size affords a brick-red coloration 

 with Millon's reagent (mercurous nitrate). Clay may furthermore be 

 made out micro-chemically in the ashes of the paper. 



Papers with Cellular Structure. 

 The so-called Chinese rice-paper and the papyrus of the ancients differ 

 completely in their microscopic properties from the papers so far consid- 

 ered. They consist principally of thin-walled, empty parenchymatic cells 

 and are obtained from the pith of soft monocotyledonous plants, by cutting 

 with a knife. 



1. Chinese, so-called rice-paper, is obtained in a spiral form from the 

 pith of Aralia papyrifera by means of a simple appliance. The sheets 

 thus obtained are then pressed and reach a size up to 11 square decimeters. 

 Each sheet consists of but a single piece 250-300 mikra in thickness. 



Smaller and poorer qualities are composed of strips, 1-2 cm. wide, ob- 

 tained from the pith by cutting radially. For this reason the latter sorts 

 appear striped longitudinally. This is, however, also partly due to the 

 fact that radially the pith is not homogenous, being made up of layers of 

 varying thickness. 



The microscope reveals polyhedric parenchymatic cells filled with air 

 which may readily be replaced by alcohol. The cells are elongated 

 longitudinally and measure 135-180 mikra in length and 54-92 mikra in 

 width. They are provided with small pores and many contain crystals of 

 calcium oxalate. 



2. The papyrus of the ancients was obtained from the tissues of the stalk- 

 of Cyperus Papyrus. This tissue consists of a loose snow-white paren- 

 chyma, resembling elderpith, in which are imbedded numerous fibro-vas- 

 cular bundles running longitudinally. The intercellular spaces, which 

 occur abundantly, also run in the same direction. 



On the fabrication of papyrus-rolls the very thin sheets cut from the 

 pith are pasted upon each other, usually three layers deep, and not paral- 

 lel, but at right angles to each other. For this reason antique papyrus 

 shows stripes, crossing each other, caused by the fibro- vascular bundles. 



The sheets cut from the pith are, according to Wiesner, about So mikra 

 in thickness. 



The parenchyma cells are large and thin walled, and usually contain 

 small crystals of calcium oxalate. 



The fibro- vascular bundles, even in older samples, are well preserved, 



