MARCHANTIA POLYMORPHA 87 



(/) In the cells of a gemma do you find chloroplasts? 



Nucleus ? Oil drops? 

 (g) Note the larger cells with clear contents from 



which the rhizoids will develop. Do they con- 

 tain chlorophyll? 

 (ti) Make a drawing 50 mm. in diameter, showing 



all the features observed under D, 2. 

 (i) Draw the outline of an imaginary cross-section 



passing through the center of a gemma. 

 The thallus. 

 (a) Under high power study the surface cells and 



stomata. How many guard-cells are there? 



Compare the stomata of Marchantia with those 



of a foliage-leaf of a higher plant, and of the 



moss and fern. 

 (6) Study cross-sections of the plant mounted in 



clearing fluid. 



(c) The careful study of the structure of the foliage- 

 leaf, already made, makes it unnecessary 

 to give detailed directions for these observa- 

 tions. Frame your own questions, to be 

 answered by observing the mounted section. 

 Note especially whether the tissues are differ- 

 entiated, and, if so, compare with a foliage-leaf 

 in this respect. 



(d) Look for sections passing through stomata, 

 and compare their structure with that of the 

 stomata of the leaf. What causes the surface 

 appearance of the margins that delimit the 

 areolae? 



(e) Describe the place and mode of origin of the 

 rhizoids; of the cupules. 



(f) Is the thallus of the same thickness throughout? 



(g) Describe the chloroplasts. In some of the 



