2518 



Journal of Applied Microscopy 



3. Study the upper surface under low power without a cover-glass, by 

 simply laying the thallus on the slide. Draw several areolae carefully. The 

 areolae represent compartments or cavities in the upper surface of the thallus. 

 The thallus should be kept moist on the under surface as it withers very rapidly. 



4. Notice the numerous rhizoids on the under surface. Where are they the 

 most numerous ? Mount some in water and draw three types under high power 

 — one with smooth wall, one with scattered peg-like projections in the interior, 

 and one with somewhat spirally-arranged projections. Of how many cells does 

 each rhizoid consist ? Of what use are the rhizoids ? 



5. With a scalpel or knife cut off some of the minute ventral scales arranged 

 in two parallel rows on the under side and forming the central ridge. Mount 

 and draw. 



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Fig. 7. — Diagram showing principal stages in the hfe cycle of the higher plants. 



6. Some of the thalli will show brood-bud cups. Under dissecting micro- 

 scope or low power draw one of the cups containing brood-buds (gemmae). 

 This is a special method of vegetative propagation. 



7. Mount some of the brood-buds. Notice the two opposite growing points 

 and the place where the brood-bud was attached to its stalk. 



S. Cut cross sections of a thallus through a cup, with a razor, and under 

 high power study the development of the brood-buds. Describe. 



9. Cut cross sections of the thallus and examine under high power. 

 Where is the main part of the chlorophyll ? Draw part of a section, showing 

 the walls of the cavities below the areolae, the peculiar chimney-like air passage, 

 the short filaments containing the chloroplasts, and the cellular tissue below the 

 cavities. These details can be worked out better from prepared slides, which 

 should be studied if available and the free hand sections used merely for com- 

 parison. 



10. Reproduce branches. Draw a plant with an archegoniophore and one 



