96 TEXTBOOK OF BOTANY 



simpler than that of a moss. In all probability, liverworts 

 and mosses are descended from green algae more or less like 

 Spirogyra, which originally lived in the water but which in 

 some long past period were forced to adapt themselves to 

 life on land. But no plants are now known, living or fossil, 

 that illustrate the steps by which such algas developed into 

 the present-day liverworts and mosses. 



