— 361 - 



The chromatophore of Urospora mirabilis *) is by Woltke (Urospora 

 p. 68) described as „eine einfache Scheibe", by Wille (Engler u. Prantl: 

 Die natürlichen Pflanzenfamilien I, 2, p. 115) as „eine wandständige, 

 durchbrochene Platte", and by Kjellman (Blastophysa och Urospora p. 12) 

 as sack-like and perforated with small, angular holes. The figures given 

 by Woltke (I.e. Tab. I) and Wille (I.e. p. 116 fig. 77^4) seem fully to 

 agree with Kjellman's more accurate description of the chromatophore. 

 Börgesen (Fær. alg. p. 502) points moreover out that the chromatophore 

 „in older, more developed cells ... is richly perforated and almost 

 quite reticular". The Icelandic specimens contain one chromatophore in 

 each cell of a shape resembling a sack with a longitudinal opening. In 

 the shorter or younger 

 cells it is perforated with 

 small, angular or round 

 holes fully agreeing with 

 Kjellman's description (1. 

 c.) and Wille's figure 

 (1. c. fig. 77, A). In ol- 

 der cells, and especially 

 in the elongated cells, the 

 chromatophore is distinct- 

 ly reticular, often with 

 great meshes(cfr.fig. 10a). 

 Regarding the shape and 

 structure of the chroma- 

 tophore , U. mirabilis 

 seems thus essentially to 

 agree with U. Worm- 

 skioldii, as the lastnamed 

 species has, as pointed 

 out by Börgesen (Fær. alg. p. 502), the chromatophores of the younger 

 cells perforated with numerous, small holes, while in older cells they are 

 distinctly reticular. The same is the case with Acrosiphonia (see later 

 p. 368) , Gladophora and several other species with perforated chrom- 

 atophores, viz. the meshes of the chromatophores in younger cells become 

 larger as the size of the cells increases. 



a 



Fig. 10. Urospora mirabilis Aresch. 

 a, b two cells showing the shape of the chrom- 

 atophore and pyrenoids of a elder cell (a) and a 

 young cell (b). The angular holes in b, are the 

 meshes (compare the text), a (400:1), & (766:1). 



') Schmitz (Ghromatophoren p. 13) describes the chromatophore of Urospora 

 mirabilis as „mehrere bandförmig oder ringförmig geformte Scheiben". As 

 pointed out by Kjellman it is highly doubtful whether the plant in question 

 described by Schmitz, belongs really to U. mirabilis Aresch.; his figure 

 (1. c. Tab. II, fig. 18) does not resemble this species. 



