THALLOPHYTA: ALGAE 



77 



tion into an outer cortical region of photosynthetic tissue and a central 

 pith that usually contains storage cells. Many of the central cells are 

 elongated and have pores in their end walls, thus resembling the sieve 

 tubes of vascular plants. Vegetative growth is not apical but results 



WMMMM^'^M 



Fig. 64. Sporangia of Lamiiiaria, intermixed with paraphyses, X400. 



Fig. 65. Gametophjtes oi Laminaria yendoana. A and B, male gametophytes, X 1,200; 

 C, a sperm, X 1,200; D, E, F, female gametophytes, X800; a, antheridia, some empty; e, 

 egg; o, oogonia; s, young sporophytes arising from the fertilized egg. (After Kanda.) 



from the activity of a meristem situated at the junction of the blade and 

 stipe. The meristem forms a new blade each year, replacing the old one, 

 which dies off. 



Numerous unicellular, club-shaped sporangia, intermingled with long 



