RICCIA. 8 1 



2. Its method of branching. 



3. Its basal and apical regions. 



4. Its differentiation into dorsal and ventral sides. 



5. The definitely organized midrib. 



6. The dark sporophyte bodies sometimes seen along the 

 midrib. 



7. Rhizoids, on the ventral surface. 



8. Draw. 



MINUTE STRUCTURE. 



Make a thin transverse section of the plant body (thallus) 

 and mount in water. 



I. VEGETATIVE STRUCTURES. Observe: 



1. Whether a distinct non-chlorophyll-bearing layer (epi- 

 dermis) is developed above and below. 



2. The rhizoids; length, structure, and the way in which they 

 are attached to the lowest layer of body cells. 



3. Structure and arrangement of chlorophyll-bearing cells, 

 the lower cells rather compact, while toward the dorsal 

 surface are rows of green cells between which are irreg- 

 ular air-spaces. 



4. Draw. 



II. SEXUAL REPRODUCTION. 



Using the same section observe that: 



1. Along the midrib sometimes there may be seen the deeply 

 imbedded flask-like archegonia and the club-shaped an- 

 theridia. 1 



2. In the swollen part, the venter of the archegonium, is the 

 central cell, which is the egg, above which is one ventral 



1 The sex-organs of Riccia are not easily demonstrated. Numerous 

 sections will be required to perform all the work outlined. Specially 

 prepared sections will be found helpful in the work. For making sec- 

 tions of liverwort sex-organs see Chamberlain's "Methods in Plant 

 Histology," p. 89. 



