Past History 



(points on the stem from which the leaves spring), 

 which so puzzle the young student of Nature when he 

 takes his walks abroad. But while the tallest of our 

 present-day native horsetails seldom exceeds 5 feet in 

 height, the ancient horsetails were tall trees, rivalling 

 in height and abundance the clubmosses of the period. 

 Like their descendants, they, too, possessed cylindrical 

 stems, leaves in whorls, and distinctly marked nodes. 



Now, it must not be imagined that these ancient 

 groups of plants, the ancestors of the British ferns, 

 clubmosses, and horsetails of to-day, were similar in 

 every detail to the now- existing species. Consider the 

 vast period of time, millions of years, which separates 

 us from the age when these ancient ferns and their 

 relatives flourished, and all the changes which the 

 world has undergone since then. Such changes, 

 scientists are always reminding us, are one of the 

 chief causes of the variations or modifications which 

 have taken place during the course of the ages in 

 plants and animals. Therefore it is not to be won- 

 dered at if our modern ferns and their allies show 

 many points of divergence from the ancient types. To 

 these changes which completely altered the face of 

 the earth we can only make a very brief reference. 

 Geologists believe that the land must have sunk 

 beneath the seas and buried the then existing vegeta- 

 tion under huge masses of sand and mud. How many 

 of these sinkings and buryings took place we need not 

 dwell on here, but we must take notice of the results 

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