PRACTICAL WORK. NO. III. 205 



No. III. 



THE ROOT. 



i. Cut accurately transverse sections of a fresh Bean 

 root, or of one that has been well hardened in alcohol, keep- 

 ing your razor well moistened with spirit. Remove your 

 sections to a watch-glass of water, taking care to keep 

 them submerged. Mount a thin section in dilute glycerine 

 and sketch it under the low power, showing 



a. piliferous layer ; 



b. cortex ; 



c. the central cylinder. 



Make a sketch of the central cylinder under high 

 power, showing 



a. the endodermis ; 

 6. the pericycle ; 



c. the xylem strands ; 



d. the phloem strands. 



ii. Cut similar sections of an older part in which 

 lateral roots are just shown on the surface and mount as 

 before. Make a sketch of a suitable section, showing under 

 a low power the lateral roots, with their root caps, piercing 

 the cortex. 



iii. Sketch a Mustard seedling to show its root- 

 hairs. They are well seen in a seedling grown in damp 

 air, but if by becoming wetted the hairs are matted 

 together, put the whole seedling into a glass of water and 

 the hairs then become obvious. 



