109 



10. Chaiitransia virgatula (Harv.) Thur. emend. 



I have for a long lime been in doubt whether the forms mentioned under this 

 species ought to be regarded as distinct species or as forms of one species. It is 

 easy to point out within tliis group of forms some fairly different types, and I 

 tried at first to carry out the first alternative, but I then repeatedly met individuals 

 which might apparently with equal right be referred to one or other of the pre- 

 sumed species. As the delimitation of the species seemed not to be facilitated by 

 the establishment of new species embracing the intermediate forms nor by divi- 

 sion otherwise of the forms, I have ended by referring them all to one species. My 

 observations have led me to the view, that this species is able to take various 

 forms under different conditions. I dare not deny that any form referred to it may 

 possibly prove on closer examination to be a distinct species, but as I have not 

 been able to draw the limits, I have judged it best to keep them together. 



The species was first described by Harvey in 1833 and figured by the same 

 author in Phyc. Brit. pi. 313 (1851), where it was represented with tetrasporangia, 

 showing even partly tetrahedral division. The last must at all events be wrong, 

 and it has also been supposed by Thuhet (Lh Jolis Liste p. 104) and later authors 

 that the statement of tetrasporangia was founded on some mistake. It was then 

 generally accepted, that this species, as well as all other species of Chantransia, 

 had only monosporangia , until Schmitz and Hauptfleisch briefly mentioned 

 (1896 p. 331) that tetrasporangia may occur together with the monosporangia in Ch. 

 secundata. Later the same was observed in Ch. virgatula by Bgrgesen and Kuckuck 

 (B0RGESEN 1902 p. 351), and the observation of Schmitz was confirmed by Borgesen 

 (1. c. p. 350) and Kylin (1907) for Ch. secundata. I have also found tetrasporangia 

 in the latter but in particular in a form coming near to the typical Ch. virgatula 

 (f. tetrica). 



As will be shown below, the forms referred to this species differ principally 

 in the nature and intensity of the ramification, the length of the cells and the 

 number of spores in the sporangia; in other respects they are quite alike. Thus, 

 the structure of the cells is the same. The chromatophore contains an axile pyre- 

 noid situated in the upper part of the cell and gives off" a number of branches 

 downwards and upwards; under the chromatophore a nucleus is visible. The ger- 

 mination takes place in the same manner in all the forms, the germinating spore 

 dividing by excentric walls into an inner triangular and three peripheral cells, 

 without changing the orbicular outline (figs. 37 C, 38 A^C, 39 C D, 40 E, 41 A), 

 (comp. Murray and Barton (1891) p. 212 pi. 37 fig. 5; Kylin (1907) fig. 24). Some 

 small differences may sometimes occur (fig. 40 h), but the greater part of the spores 

 germinate as described. The orbicular outline of the basal disc may sometimes 

 hold out for a long time, in other cases some of the peripheral cells grow out to 

 creeping filaments at an early period (figs. 39, 40). The number of erect filaments 

 given oft" from the basal disc is usually low; the first is produced by the central 

 triangular cell, the following from the neighbouring cells. 



