226 PRACTICAL BOTANY. 



As these exercises presuppose the previous study of the 

 gross morphology and the analysis of a considerable num- 

 ber of the plants of this subclass, the practical studies will 

 be directed to the minute anatomy of typical plants, with 

 the particular purpose of preparing for the consideration 

 of the physiology of the higher plants which follows. 



THE DICOTYLEDONS. PRACTICAL STUDIES. 



1. Examine bits of the epidermis torn from both the 

 upper and under surfaces of the leaves and from the young 



and tender stems of a number of 

 different plants ; almost any of the 

 Dicotyledons will do : Nasturtium, 

 Sunflower, Bean, Shepherd's Purse, 

 Cabbage, Beech, Deutzia, and Fuchsia 

 are good. Mount in distilled water, 

 and, after observing the shape of the 

 stoma, note the changes brought 

 about by plasmolyzing with salt solu- 

 tion. Do you find stomata in equal 

 numbers on both the upper and the 

 FIG. 144. stomata of lower sides of the leaf ? Do you find 



Lilac leaf. ,-, .^ . i * .*, 



them on the epidermis of the stem? 



Draw stomata as found on several different leaves, to- 

 gether with their guard cells and a few cells of the sur- 

 rounding epidermal tissue. Do you find chlorophyl in 

 the guard cells? In the epidermal cells? Do you find a 

 nucleus and nucleolus in the guard cells ? In the epider- 

 mal cells? 



2. Place parts of leaves between pieces of pith, and cut 

 transverse sections. Notice carefully in what parts of the 

 section chlorophyl is found. Draw and label as many of 

 the parts as you can by comparison with Fig. 145, which 

 is a transverse section of a leaf of the Rubber Plant, Ficus 



