METHODS OF PRESERVATION 13 



Tertiary age, will furnish quantities of the fruits and seeds of by- 

 gone forests that flourished on their sites. Peat bogs are veritable 

 mines of more recent vegetable history and where their contents 

 are studied intensively as in some of the European countries they 

 record the changes from sphagnum to rushes and the succession 

 of willow, birch, pine and hazel much more certainly decipherable 

 than the early written records of human history. Amber and 

 other gums frequently contain small plant fragments in an exquisite 

 state of preservation but the great bulk of fossil foliage was buried 

 in shallow water muds of flood plains, lakes, bayous and estuaries 

 and lagoons. Occasionally lignified wood may retain its internal 

 structure and by special methods of treatment it may be sectioned 

 and studied microscopically. 



The details of the past history of our forest trees will doubtless 

 always remain imperfectly known but this knowledge is increasing 

 rapidly and we can already sketch the broader outlines of the his- 

 tory of a large number of our trees as the present sketches bear 

 witness, and we can leave to the future the filling in of the details 

 of these pictures when we know that these broader outlines are 

 not founded upon fancies or theory, but upon facts. 



