PLATE XIII. 



Nitella gracilis Agardh. 



FIG. 



1. Plant, natural size, from Perranzabuloe, Cornwall. 



2. Ultimate node of branchlet, showing 2- and 3-celled 



dactyls, x c. 40. 

 3, 4. Apices of dactyls, x c. 40. 



5. Fruiting branchlet. x c. 20. 



6. Oogonium. x c. 40. 



7. Oospore. x c. 40. 



