124 



the plant assumes an often quite bluish-green colour while in 

 places more protected against the light its colour is a dark red- 

 brown or red-violet; by drying the blue-green specimens assume 

 mostly a dark red-brown colour. 



The ramification is monopodial. It is a very variable plant ; 

 in some specimens the branches are long in others short, in 

 some the length of the branches grow evenly shorter upwards 

 in others they are longer and more vigorous upwards and much 

 ramified. Some specimens have a proportionally broad thallus in 

 others the filaments are nearly thread-like. In some specimens 

 the main filament bears along its whole length rather short un- 

 divided branches. KUTZING has figured several of these forms in 

 his Tabulae Phycologica?. 



A transverse section shows the structure commonly found 

 in Grateloupia. The medullary layer is very loose in the middle, 

 denser towards the periphery where it goes rather evenly over 

 into the cortical layer. The filaments in the medullary layer are 

 about 8/4 thick; they are irregularly subdichotomously ramified 

 and felted between each other. 



The cortical layer consists of short closely packed filaments 

 whose innermost cells are nearly spherical, oblong to subcylindric 

 at the periphery. 



The tetraspores are formed in great numbers over the whole 

 thallus in the cortical layer; they are cruciately divided. 



The antheridia and cystocarps occur in the same plant as 

 pointed out by BERTHOLD. 



The antheridia are formed of the peripheral cells in the cortical 

 layer as a kind of outgrowth from these; the spermatia are small 

 spherical bodies about 4 5 p in diameter. 



The cystocarps occur more or less over the whole surface of 

 the thallus. They are spherical bodies about 180 fj. in diameter 

 and reach far into the medullary tissue. The wall is well developed 

 formed by filaments growing out from the auxiliary cell filaments. 

 The cystocarps discharge by means of a pore through the cor- 

 tical layer. The carpospores are densely crowded together forming 

 a nearly spherical body. They are about 18 20 p in diameter. 



With the exception of the most exposed localities this species is com- 

 mon along the shores of the Danish Isles. 



Geogr. Distrib. : Seems to occur in all warmer seas. 



2. Grateloupia diehotoma J. Ag. 



J.AGARDH, Algae mar. Mediterr., 1842, p. 103. KUTZING, Spec. Alg., p. 732; 

 Tabulae Phycologicse, vol. XVII, tab. 28, figs, c e. J. AGARDH, Epicr., p. 152. 



