F. Børgesen: Rhodophyceæ of the D.anish W. Indies. 



127 



Fig. 135. Grateloupia cuneifolia J. Ag. 



Transverse section of the thallus with 



tetrasporangia. (About 550 : 1). 



ramified filaments running between each other in all directions in 



the mucilage found here. 



In a longitudinal section it is seen that the medullary cells 



are very irregularly branched 



often more or less starlike 



(Fig. 136); the breadth of 



the cells is also very vari- 

 able and this is also the 



case regarding the length 



of the cells. The develop- 

 ment of these starlike cells 



is just the same as is de- 

 scribed by Berthold (1. c, 



p. 2) for Halymenia. The 



filaments having got some 



length swell at the end 



and from this thickened 



part filaments grow out in all 



directions ; the ends of some 



of these filaments meet other 



similar ones and fuse together 



with them or their ends swell and give rise to new star-like cells. 



The cortical layer is 

 composed of short dichoto- 

 mously ramified filament;?. 

 The innermost cells in 

 these are the largest and 

 more irregularly shaped, 

 the outermost small oval 

 to subcylindrical 8 — 9 /i 

 long and about 3 // broad 

 and rather closely packed 

 together. 



The tetrasporangia (Fig. 

 135) are formed in the 

 cortical layer and occur 

 scattered over the whole 



surface of the thallus. They are cruciately divided about 30;/ 



long and 19 fi broad. 



Among the dried specimens a single cystocarpic one was 

 found. While the tetrasporic specimens have quite a smooth sur- 



Fig. 136. Grateloupia cuneifolia J. Ag. 



Star-like cells from the medullary layer. 



(About 250:1). 



