Fig. 97 Laminaria. A, L. cloustoni. B, L. rodriguezii. C-E, normal 



regeneration ( x i). C, rupture just commencing. D, E, the new 



tissues are more' heavily shaded. F, woimd regeneration ( x ^). 



(A, B, after Oltmanns; C-F, after Setchell.) 



frayed ends of the non-growing outer cortex forming collars, 

 the upper one of which rapidly wears away. After the rupture 

 the new cells of the medulla and inner cortex elongate 

 rapidly. The failure of the outer cortex to grow is probably 

 associated with the proximity of the inner cortical cells to the 

 medullary hyphae where they can monopoHze all the grow- 

 ing materials, thus cutting off any supply to the outer cortex, 

 but there may, of course be other factors involved. 



(3) Restorative regeneration whereby branches arise from 

 wounded surfaces, the same tissues being involved as in 

 process (2) (cf Fig. 97). 



A detailed study of growth in L. saccharina (by Parke, 1948) has 

 shown that in this species the longevity and rate of growth of the 



173 



