lOO 



PLANT ORGANS OR PARTS OF PLANTS. 



may be encountered. These express, however, the aver- 

 ages of a large number of examinations. 



The ducts of belladonna root are manifest ; few spirals 

 are found, and a number of reticulated and pitted forms 

 and varieties with bordered pores ; much range in diam- 



FiG. i6. — Belladonna. 

 S.V., Spiral vessels; C.T., corky tissue; TR., tracheids; PAR., pa- 

 renchyma; Pt. Duct, pitted duct; S., starch; F,, fibres; R.D., reticu- 

 lated duct. 



eter of these ducts is to be observed. The average of 

 several measurements gave : Spiral ducts, i8; reticulated 

 ducts, 25; pored ducts, 40 microns. 



The tracheids are typical and prominent ; their average 

 diameter is about 30 microns. They frequently are very 



