514 Howe: Phycological studies 



4. Cortical cells in surface view, from a glycerin mount, in which the boun- 

 daries of the cell walls are too indistinct to be drawn with accuracy. 



5. A similar view in an older part of the thallus, with the cell walls more swollen 

 and the protoplasts more widely separated. 



6. Cortical cells in surface view, after staining with haematoxylin and treat- 

 ment with KOH. The grouping of the cells indicates more or less clearly their 

 relations to the subcortical cells; e. g., the upper group of six cells crowns a single 

 subcortical cell. 



7. A stellate or radiate termination of one of the medullary filaments. 



8. 9. Capitate and stellately branched terminations of the medullary filaments 

 in more detail. The pedicel in each figure shows the beginning of a lateral branch. 



10. Cells of the subcortex, showing connections and mode of branching. 



11. A somewhat flattened branched cell of a form that occurs in the subcortex 

 about halfway between the cortex and the capitate terminations of the medullary 

 filaments. 



12. A portion of a medullary filament terminating in the subcortex and showing 

 the beginnings of two lateral branches. The terminal cell of such branches carries 

 a dense and conspicuous protoplast. 



13. Stellately branched subcortical cells from a young part of the thallus, one 

 of them showing 13 branches. These branches connect with other similar, but 

 mostly smaller and more peripheral cells, from which they have been detached. 



Figures 1-6, 8, 9, 11, and 12 are enlarged 276 diameters; 7 and 10, 46 diameters; 

 13, 244 diameters. The sections and fragments from which figures 2, 3, 6, 7-10, 12, 

 and 13 were drawn were stained with haematoxylin and then swollen out with a 

 solution of KOH; in figures 2, 3, 8, and 9, the thickness of the gelatinous cell walls 

 and probably the dimensions of the parts in general have been somewhat exag- 

 gerated by an excess of KOH. Figure ii was drawn from material that had been 

 stained with picric-nigrosin. 



