222 PLANT ORGANS OR PARTS OF PLANTS. 



the Upper part of stem, and the flower axis; (3) shorter, 

 broad, falciform hairs, with rounded mass-like collec- 

 tions of calcium carbonate at the base of the hair ; these 

 are the cystoliths, and occur on the upper leaf surface. 

 The glands proper are rounded and multicellular, sac- 

 like in general shape, and form a conspicuous feature in 

 a good powder. In size they range from 20 to 60 microns. 

 They may be stalked or sessile. Pollen grains are few 

 and may readily be overlooked. They are spherical and 

 regularly marked. Crystals of calcium oxalate of the 

 rosette-shaped variety are also few and inconspicuous. 

 These average about 20 microns in diameter. The 

 parenchyma is thin- walled and lax, and the cells often 

 appressed and gummed together by the resin masses 

 which show as brown and blackish bodies throughout 

 the powder. These irregular masses form a very con- 

 spicuous part of the powder. The resin masses and 

 hairs are sufficient for making a diagnosis of the powder. 



Epidermal cells with stomata are occasionally found. 

 The fibres and vessel elements vary widely in quantity. 

 In some powders fibres are common, and also spiral, 

 annular, and reticulated ducts ; in others these elements 

 are fewer. This depends upon the amount and the de- 

 velopment of the stem, which may be included. The 

 seeds show stone cells and small, irregular, twisted, and 

 contorted epidermal cells. These are diagnostic of them- 

 selves. Attached to these seed elements are cells con- 

 taining small masses of starch grains and sometimes 

 masses of aleurone grains. 



Chemistry. — Indian hemp contains about 20 per cent, 

 resin. A brown, alcoholic extract obtained from this is 

 known as cannabin, and from this oxycannabin has been 

 isolated. The alkaloid cannabinine also occurs. 



