F. Børgesen: Phæophyceæ of the Danish W. Indies. 



47 



In the basal part the cell walls are very thick and numerous 

 rhizoids grow out from the surface cells on both side of the 

 thallus. These rhizoids consist of thickwalled, nearly cylindrical 



Fig. 29. Padina gymnospora (Kütz.) Vickers. 



a, transverse section of thallus with emptied and not emptied tetraspor- 



angia and hairs, b, surface of thallus with tetrasporangia. c, lower face of 



thallus with hairs, d, transverse section of thallus near the base. 



(About 90: 1). 



