6 2 HIS TOR Y OF COHASSE T. 



Prof. Asa Gray * has given a convincing account of 

 the retreat of the North American forest to the south be- 

 fore the growing glacier, and of its return to its present 

 state upon the departure of the glacier. How slowly the 

 edge of the prehistoric forest spread towards the north 

 when the arctic rigors retreated is left to be imagined. 



Each tree casts a myriad seeds ; some few take root. 

 Perhaps a favorable wind might be able to bear a maple 

 seed a quarter of a mile, or some gale of winter might rap 

 a pine cone against a limb so as to loosen a seed that would 

 sail even farther towards the barren hills. After fifteen or 

 twenty years perhaps those seeds might have become trees 

 large enough to send their progeny still farther pioneering 

 towards the north. Steadily onward the vanguard of the 

 forest made its way, while every shrub and vine and grass 

 kept pace with the migrations, when a favorable wind 

 could be chartered or some animal or bird induced to bear 

 the seeds along. 



The pilgrims that came first to Plymouth, after Plym- 

 outh Rock itself got pushed there, were the enterpris- 

 ing: trees from the south. Cohasset was reached not 

 long after, and the plant settlement grew thicker each 

 year upon the drumlins which had remained comparatively 

 bare for perhaps several hundred years. 



The covering of pines and oaks and ashes and beeches 

 and birches and savins was interlaced by witch-hazels and 

 sumacs and laurels of shorter growth, and by the still 

 shorter shrubs and by vines. The grasses were a very 

 important textile in the garment of vegetation. There 

 was none of the good fleshy English grass such as had to 

 be imported for the cattle of our pioneer ancestors ; but 

 even the wild grasses increased the fertility of the soil, 

 and one kind of native grass, that gigantic variety known 



* Forest Geography and Archaeology, a lecture before the Harvard University 

 Natural History Society, April 18,1878. Printed in American Journal of Science, 

 Vol. CXVI, pp. 85-94, 183-196. 



