INFLUENCE OF EXTERNAL STIMULI. LIGHT 



2 33 



Hypnum splendens, Thuidium, and others. The position of the leaves in 

 these latter forms is still completely radial whilst the branches are arranged 

 in one plane; but there are also on other positions on the shoot-axis 

 primordia of twigs, although, as I think, in less number than the lateral ones. 

 The primitive constitution of the branching is then not entirely bilateral, 

 but only the primordia of lateral twigs develop. This arrangement is 



FlG. 114. Funaria hygroinetrica. Protonema produced 

 in darkness. Highly magnified. 



brought about by light, and the primordia of the twigs of the illuminated 

 side and of the shaded side do not come to development (see Fig. 113). 

 Innovation-shoots of Hypnum splendens developed in cultivation upon 

 the klinostat under a varying illumination produced, according to Coesfeld l , 

 branches in every direction. 



1 Coesfeld, Beitr. zur Anatomic und Physiologic derLaubmoose, in Botan. Zeitung, 1892, p. 187. The 

 results require confirmation in several directions, especially where the intensity of light is concerned. 



