MARCHANTIA POLYMORPHA 95 



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 growths? 

 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, (#)-(/), 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? 



