302 MINNESOTA BOTANICAL STUDIES. 



3. A portion of the central axis showing a branch which is leaving 

 it. Protoplasmic axis of the central cylinder. The protoplasm 

 appears to separate into threads to pass] through the thickened plate. 



4. Longitudinal section of frond. Axis cylinder surrounded by 

 mucilaginous sheath. This figure illustrates the point that the main 

 branches from the axis cylinder do not run out radially, but diagonally 

 upward, reaching the periphery opposite the lower end of the third 

 cell of the central axis from which they started. 



5. Cystocarp containing carpospores; filaments ramifying among 

 he spores. 



6. Carpospores and branching filaments. 



7. Holdfast. #, horizontal branch; ^, stipe; c, brown cellular 

 substance developed beneath the holdfast; d, vertical branch. 



8. Section showing tetragonidangia and paraphyses in different 

 stages. 



