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the struggle for existence. As Darwin wrote in a 

 letter to Sir Joseph Hooker in 1881, 'Nothing is 

 more extraordinary in the history of the vegetable 

 kingdom, as it seems to me, than the apparently 

 very sudden or abrupt development of the higher 

 plants(ii).' In another letter (1879) to the same friend 

 we read, 'The rapid development as far as we can 

 judge of all the higher plants within recent geological 

 times is an abominable mystery (12).' Making allow- 

 ance for the probability, or indeed certainty, that 

 the imperfection of the geological record tends to 

 exaggerate the apparent suddenness of the ap- 

 pearance of this vigorous class, and allowing for 

 the fact that our knowledge of the records of 

 the rocks in which the highest plants first occur 

 is very incomplete, we cannot escape from the 

 conclusion that this recently evolved group spread 

 with amazing rapidity. Various reasons may be 

 suggested in explanation of the dominant position 

 Avhich the Angiosperms hold in the floras of the 

 world. As an instance of their rapid increase during 

 the Cretaceous epoch ^, the period which has furnished 

 the earliest satisfactory records of Flowering Plants, 

 the following statement by an American writer may 

 be quoted : — ' The rapidity with which it [/.e. the 

 group of Flowering Plants] advanced, conquering or 



1 For the position of the Cretaceous and other systems in the 

 geological series, see the table on page 42. 



