MARCHANTIA POLYMORPHA 89 



structures borne? On which surface do they 

 originate? State their average height in milli- 

 meters. Describe the grooves on the surface. 

 How many are there? 



(c) Describe the color of the stalk. Are stomata 

 present ? Epidermal hairs or other outgrowths ? 

 If so, describe. 



(d) Do you find any antheridiophores that branch? 



(e) Describe carefully the appearance of the upper 

 surface of the antheridial receptacle, noting 

 the occurrence and distribution of any struc- 

 tures or surface marks. 



(/) Is this surface perfectly plane? If not, describe. 



(g) Make drawings, twice natural size, showing 

 all points observed under F, i, (a)-(f), including 

 a cross-sectional view of the stalk. 

 Microscopic Characters: 



(ti) Study and describe with drawings .(5 cm. 

 in diameter), the structure of the stalk of 

 an antheridiophore as seen in cross-section. 



(i) Using prepared slides, study thin longitudinal 

 sections passing through a receptacle and 

 portion of the stalk. Is there a differentiation 

 into epidermis and other tissues? Describe 

 in detail. Note the intercellular air-spaces. 

 In what part of the structure do they occur? 

 Suggest any advantage these air-spaces may be 

 to the plant. 



(k) Observe the chambers opening at the surface 

 through necks, and containing the antheridia. 

 How many antheridia in each chamber? De- 

 scribe their shape, and mode of attachment. 

 How many cells thick is the wall of the anther- 

 idium? Do the wall-cells contain chlorophyll? 



