CORD AIT ALES 183 



both come from the same section of that group. Some Pteridophyte 

 with compound leaves and a stem with large pith, scanty wood, and 

 large cortex, may have given rise to the Cycadophytes; while an- 

 other, with similar stem structure, but with simple leaves, may have 

 been the ancestor of the Coniferophytes. 



When the Hfe-histories of the Paleozoic forms become better 

 known, there will be a firmer foundation for theories, and theorizing 

 will not be so easy. With only a few facts to reconcile, any theory will 

 do; but when facts become numerous, a theory reconciling all the 

 facts is more difificult to formulate. 



