F, Borgesen: Rhodophyceæ of the Danish W. Indies. 



103 



Fig. 110. Galaxaura squalida Kjellm. 

 Transverse section of the thaUus show- 

 ing the periferic tissue with chroma- 

 tophores and pyrenoids. (About 250:1), 



of numerous irregularly bent filaments felted together ; these fila- 

 ments have fairly thick walls and a breadth of about 16 /i while 

 their length is often up to ten times the breadth. 



From this base several branches grow up and these are re- 

 peatedly dichotomously ramified. The internodes are of very 

 variable length from one to 

 two cms. The branches are 

 cylindrical, also in the dried 

 condition, with the exception 

 of the quite young upper ends, 

 not yet much incrusted which 

 collapse being more or less 

 flat when dry. In the spirit 

 material the apices are nearly 

 cup-shaped with the sunken 

 growing point in the middle. 

 The colour of the dried 

 plant is a sordid yellow-green 

 with a red-brown tinge espe- 

 cially where the assimilating 



hairs are present. These do not occur evenly distributed over 

 the whole surface; they are most numerously present upon the 

 younger parts of the branches and often show here an annular 

 arrangement but quite scattered ones also often occur especially 

 upon older parts of the thallus. 



The surface of the plant is mostly rather clearly annulated. 



A transverse section shows that the 

 medullary tissue is composed of rather thick- 

 walled dichotomously branched filaments con- 

 sisting of long cylindrical cells of which the 

 diameter varies from 7 to 16 /i. The periferal 

 tissue consists of short often dichotomously 

 ramified cell-threads composed of 3—4 cells 

 (Figs. 109, 110). Of these the innermost are 

 the largest; they are mostly roundish but 

 very large ones, irregularly shaped and lobed 

 are often found (Figs. 109, 111). These lobed cells are also men- 

 tioned and figured by Kjellman and occur in several other 

 species. This cell layer is about 40 /i thick, but the cells are 

 very variable in size the large lobed cells being often much thicker. 

 These cells are colourless and contain only protoplasm, cell sap etc. 

 The next cells are smaller (about 25— 30/i in diameter), nearly 



Fig. 111. Galaxaura 

 squalida Kjellm, A 

 lobed cell from the 



periferic tissue. 



(About 200:1). 



