264 



F. B0RGESEN 



Scattered over the whole surface there are cryptostomata, generally rather 

 shallow depressions, from the bottom of which hairs grow out to form rather 

 long and dense, brushlike tufts. The blunt summit of the thallus has no hair- 

 groups contrary to Skottsberg's Cladochroa. 



A transverse section of the thallus (Fig. 12 d) exhibits a cortical layer of 

 oblong or short cylindrical cells, having nearly the same aspect on a longitudinal 

 section; the parenchymatic tissue inside consists of rather thickwalled cells, 

 oblong to subcylindrical in longitudinal, more sphaerical in transverse sections. 



Fig. 12. Chnoospora fastigiata J. Ag. a Transverse section of the thallus with plurilocular 



sporangia and hairs, c. 400 /i; b longitudinal section of apex of a branch, c. 800 /i; c longitudinal 



section of thallus, c. ,40 /i; d transverse section of thallus, c. M0 /i. 



In the growth-point no marked top cell is present. As figure 12 b shows, 

 the longitudinal growth takes place by means of a series of cells at the apex 

 of the filaments, the lower part of these cells being gradually cut off. 



The figure of the growth point in our plant is very like those of Scyto- 

 thamnus australis and Coilodesme bulligera (comp. Oltmanns, Morphologie unci 

 Biologie der Algen, vol. II, 1922, p. 62) as drawn by KUCKUCK and found 

 among his posthumous prepatory notes to the great work on the Phaeophyceae 

 that was never completed, much to the regret of all algologists. According 

 to Oltmanns the notes of KUCKUCK regarding this matter are quite frag- 

 mentary. 



