366 Pub. Puget Sound Biol. Sta. Vol, 2, No. 53 



PLATE 63 



Origin of cortical layer in Desmarestia ligulata (Lightfoot) Lamouroux, 

 partly diagrammatic. a. Intercalary growing region; b. Base of 

 terminal hair; c^ Bases of lateral hair branches; d, Basal growing 

 region of branches; e, Permanent axis of thallus ; f. Bases of lateral 

 branches of permanent axis; g, Intercalary growing region of branch; 

 h, First cell cut off in formation of cortex ; i, Second cell cut oft' in 

 formation of cortex; j, Cortication complete; k. Cells of original thallus 

 covered by cortex. 



