84 MORPHOLOGY AND LIFE HISTORY 



If they are, describe them and their distribution. 

 Compare them with the stomata of a foliage-leaf 

 of one of the higher plants, including the number, 

 shape, and other characters of the guard-cells. In 

 like manner compare them with the stomata of the 

 fern. State, with reasons, which type of stomata 

 you consider the more primitive. Look for stomata 

 on the surface of the apophysis. 



3. Study thin cross-sections of the sporangium (sec- 

 tions of the half (C, 18) will serve). Identify the 

 parts already studied, and their characters and 

 relationship as seen in cross-section. Make your 

 drawings at least 20 mm. in radius. 



4. Describe the shape of the spores, and their manner 

 of attachment or non-attachment, as seen under 

 high power. Of how many cells is one spore com- 

 posed? Make a drawing of three spores making 

 each 10 mm. in longest measure. 



5. Mount thin cross-sections of the seta, and study 

 under high power. 



6. Distinguish the outer layer, epidermis. How 

 many cells thick is it? Observe the central strand, 

 and between this and the epidermis a thin-walled 

 tissue (parenchyma), and a layer of thicker walled 

 cells (sclerenchyma). State how these various 

 tissues may be distinguished from each other. Of 

 what value is the sclerenchyma? The central 

 strand is comparable with the nbro-vascular bundle 

 of the seed-bearing plants. Draw. 



THE GAMETOPHYTE 

 The Leaf. 



7. Remove an entire leaf and mount it in water. Ob- 

 serve under low, then under high power. 



