82 A LIVERWORT. 



canal cell, and a row of neck canal cells, enclosed by the 

 neck wall cells. In archegonia which contain fertilized 

 eggs the canal cells have disappeared, having become dis- 

 organized to permit the access of the sperms to the eggs. 



3. Draw. 

 Observe also: 



4. The antheridium, a club-shaped organ, consisting of a 

 layer of wall cells and many small sperm mother-cells. 

 In fresh material sperms may sometimes be seen as they 

 escape from the antheridium. 



5. Draw. 



6. Archegonia which contain germinating oospores. 



7. Draw. 



III. ASEXUAL REPRODUCTION. 



1. If the section is especially favorable, note the different 

 stages in the germination of the oospores, resulting finally 

 in the formation of the fully formed sporophyte (or spo- 

 rogoniurri), consisting of: 



(a) A single outside layer of cells constituting the wall 

 which early disappears, and 

 (6) A mass of asexual spores. 



2. Draw. 



ANNOTATIONS. 



The general form and structure of Riccia suggest 

 Coleochcete, the highest member of the Chlorophyceae 

 that we have examined, but Riccia is very much more 

 highly differentiated both for nutritive and reproductive 

 work. The prostrate branching body of Riccia is 

 differentiated in that it is distinctly dorsiventral, has on 

 its ventral side rhizoids which perhaps assist in obtaining 

 water and its solutes and serve also to anchor it. The 



