PRACTICAL WORK. NO. VIII. 213 



leaves on the stem. Count (a) the number of leaves you 

 pass and (b) how many times you pass round the stem 

 before a leaf is found whose position is exactly above that 

 from which you began. 



v. Examine a branch of Horse-chestnut (^Esculus 

 hippocastanum). Shew on your sketch the scars of the 

 leaves and of the vessels of their bundles ; also the scars 

 of the scale-leaves at the base of each year's shoot, which 

 scales at one time covered the winter bud. 



vi. Cut and sketch a longitudinal section of the 

 swollen base of a leaf-stalk of Poplar and of the stem to 

 which it is attached, shewing 



a. stem bundles ; 



b. leaf bundles ; 



c. outline (epidermis) of stem and petiole ; 



d. the absciss layer across the swollen base of the 

 petiole which permits the leaf to fall, and forms a layer 

 of cork covering the scar made by the loss of the leaf. 



No. VIII. 



REPRODUCTION. 



I. Pleurococcus. 



i. Mount in water a small quantity of the green 

 powder found on trunks of trees or damp wood, and ex- 

 amine it with the high power. Make sketches to shew : 



a. a single cell ; its cell- wall, and the contained proto- 

 plasm coloured green ; 



b. cells in various stages of division. 



