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



289 



of these soon increases in the following segment, until the same 

 number is reached as found in the main stem. The number of 

 segments in each branchlet seems to vary considerably; in my 

 plants the branchlets are rather short, having only 10 — 13 seg- 

 ments. Ambronn on the other hand (1. c, p. 211) has found up 

 to 40 in each branchlet. The segments in my plants were about 

 60 fi long and the diameter of the branchlet about 45 fx. The 

 length of the whole branchlet was about 1mm. 



Fig. 289. Herposijihonia tenella (C. Ag.) Nagl. Part of a plant with irregular 

 ramification and a scheme of it seen from above. (About 30:1). 



The branchlets bear in their summit two trichoblasts, or 

 rarely only a single one; the development of these is given by 

 Ambronn (1. c, p. 214 — 5, pi. IV, fig. 15), 



Only plants with tetrasporangia were found. These (Fig. 288 a) 

 are developed in the branchlets, a single one in each segment, 

 and, in my specimens, seldom more than 6 in each branchlet, 

 while Falkenberg has found up to 20—30 sporangia in each 

 branchlet. Owing to this fact and in general owing to the 

 very few segments found in the branchlets, my specimens ap- 

 proach Herposiphonia secunda (comp, Falkenberg, 1. c, p. 308) 

 and this is still more the case with regard to some other speci- 

 mens found on the shore of St, Jan. 



Here a form was found with very short segments (Fig. 289), 

 and as it also showed some irregularities in the arrangement 



Dansk Botanisk Arkiv, Bd. 3. Js'r. 1 (1918). 19 



