FOREST GEOGRAPHY AND ARCHAEOLOGY. 233 



the period of refrigeration, deeply covered a very large part 

 of the forest-area ; much to the narrowness of the forest-belt, 

 to the want of summer rain, and to the most unequal and 

 precarious distribution of that of winter. 



Upon all these topics questions present themselves which 

 we are not prepared to discuss. I have done all that I could 

 hope to do in one lecture if I have distinctly shown that the 

 races of trees, like the races of men, have come down to us 

 through a prehistoric (or pre-natural historic) period ; and 

 that the explanation of the present condition is to be sought 

 in the past, and traced in vestiges and remains and survi- 

 vals ; that for the vegetable kingdom also there is a veritable 

 Archseology. 



