306 



Ulotrichales 



The branches of Trentepohlia are usually bluntly rounded and growth is 

 entirely apical. The cell-walls are lamellate and the lamellae consist of 

 cellulose. In some species the lamellae are approximately parallel and the 

 growth of the apical cell takes place by the proportionate distention and 

 permanent increase in area of all the layers. In other species the lamellae 

 diverge upwardly and outwardly, and the growth of the apical cell takes place 



Fig. 199. A C, Trentepohlia aurea (L.) Mart. var. laiiosa Kiitz., x 500. 

 D F, T. calamicola (Zell.) De Toni, x 500. zg, zoogonidangium. 



by the distension of only the newly formed layers, the older layers being 

 burst through. In T. Montis-Tabula? var. ceylanica all the layers of the 

 cell-wall are burst through at the apex by the extension of the last-formed 

 lamella (fig. 200). In many species of the genus apical caps of pectose are 

 secreted at the free end of the apical cell. These caps vary in the extent 

 of their development ; they are for the most part absent in species in which 



