ORGANIC EVOLUTION" 



119 



to the soil. It is of bright green color, and has a peculiar, 

 and seemingly incongruous musty odor. It grows apically, 

 in a zig-zag course, dichotomously branching alternately 

 to right and to left, the branches and parent stem being 

 of equal breadth. 



If we tear up a little strip of the thallus from the soil, we 

 shall observe at once a considerable number of parts not seen 

 among the algae. First, there is a multitude of slender 



FIG. 69. Photographs of the liverwort Conocephalus; the larger figure is an enlarged top 

 view of the thallus; the smaller one a side view of an old specimen bearing sporophytes. 



white rhizoids, holding the plant body fast to the soil. 

 These are feeding organs. A number of algae (for example, 

 Chara, and Nitella) have similar organs for attachment, but 

 they are much less developed and have no feeding function. 

 In the liverwort, as in most of the higher plants, rhizoids 

 are the chief means of taking up dissolved mineral sub- 

 stances out of the soil. The torn end of the thallus will 

 show, also, that the plant body is covered with a dry surface 



