174 ANCIENT PLANTS 



and as our knowledge of fossil anatomy and of recent 

 ecology increases, their evidence will become still more 

 weighty. Even now, had we no other sources of in- 

 formation, we could tell from the plants alone where in 

 the past continents were snow and ice, heat and drought, 

 swamps and hilly land. However different in their 

 systematic position or scale of evolutional development, 

 plants have always had similar minute structure and 

 similar physiological response to the conditions of climate 

 and land surface, so that in their petrified cells are pre- 

 served the histories of countries and conditions long 

 past. 



CHAPTER XIX 

 CONCLUSION 



In the stupendous pageant of living things which 

 moves through creation, the plants have a place unique 

 and vitally important. Yet so quietly and so slowly 

 do they live and move that we in our hasty motion often 

 forget that they, equally with ourselves, belong to the 

 living and evolving organisms. When we look at the 

 relative structures of plants divided by long intervals 

 of time we can recognize the progress they make; and 

 this is what we do in the study of fossil botany. We 

 can place the salient features of the flora of Palaeozoic 

 and Mesozoic eras in a few pages of print, and the con- 

 trast becomes surprising. But the actual distance in 

 time between these two types of plants is immense, and 

 must have extended over several million years; indeed 

 to speak of years becomes meaningless, for the duration 

 of the periods must have been so vast that they pass 

 beyond our mental grasp. In these periods we find a 

 contrast in the characters of the plants as striking as that 

 in the characters of the animals. Whole families died 

 out, and new ones arose of more complex and advanced 



