EXPLANATION OF THE PLATES. 499 

 PLATE III. 



Figs. 1 8. AcJdya prolifera Nees. 



Clavate expanded extremities of the branches. 



1 . Part of the contents form an elliptical accumulation, 

 which loses itself pretty gradually, externally, in the 

 remainder of the cell-contents, and from which radiating 

 threads of circulation proceed. 



2. The elliptical accumulation presents a better de- 

 fined outline ; there are still some few threads of circula- 

 tion. 



3. The agglomerated portion of contents has become 

 converted into a cell (sporangium) by the formation of a 

 membrane. This is densely filled with granular mucilage. 



4. The sporangium-cell is filled with dark, granular 

 contents, and inclosed by a tolerably thick membrane. 

 It has grown out, upward, and downward, into two pro- 

 cesses (branches). These have a delicate membrane and 

 contents, consisting of mucilage, homogeneous towards the 

 summit at least. They elongate by apical growth. 



5. Three free sporangial cells have been formed in the 

 end of a branch. They contain homogeneous mucilage. 



6. Two free sporangial cells, each of which has grown 

 out into a process. One sporangium is densely filled with 

 minute cellules. The other has already discharged the 

 greater part of the motile cellules through the opening of 

 the apex of the process. 



7. The entire end of the branch has become a spo- 

 rangium, the whole of the contents having become isolated 

 and converted into a cell by parietal cell-formation. This 

 is filled with granular mucilage. 



8. As in fig. 7. The sporangium has grown out at 

 the apex into a short process. It is crowded with minute 

 cellules. 



