VITALITY OF SEEDS. 23 



tation is supposed to have been nearly all destroyed, 

 as far south, at least, as Alabama and Texas. How 

 then came the continent to be re-clothed when 

 the glaciers receded to the northward, leaving im- 

 mense deposits of sand and gravel and barren rock 

 in place of the original prairies and forests ? This is 

 the question Professor Winchell endeavors to 

 answer. In the work referred to, in a chapter on 

 the "Vitality of Buried Vegetable Germs," he says: 



" For some years past I have been inclined to 

 believe that the germs of vegetation which nour- 

 ished upon our continent previous to the reign of 

 ice, and many of which must have been buried from 

 twenty to one hundred feet beneath the surface of 

 the glacial rubbish, may have retained their vitality 

 for thousands of years, or even to the present 

 time." Facts, he says, show the presence of grains 

 " where they could not probably have been intro- 

 duced during the human epoch." 



The remains of ancient vegetation are abundantly 

 sufficient in all the glacial region of the northern 

 hemisphere to have supplied these germs had they 

 retained their vitality, and the gradual washing 

 away of the surface by streams has been a sufficient 

 means of bringing them to the surface. In his 

 remarks upon ancient forests, Professor Winchell 

 says: 



