VI PREFACE 



terminology of the tissues of the root has been revised 

 in accordance with recent views. 



A chapter has been devoted to the Charaeese, which 

 were entirely omitted in previous editions ; various 

 subsidiary types have been introduced here and there 

 in the text in small print, with a view to extending the 

 course beyond the dangerously narrow limits of pure 

 type-teaching. These and other alterations have been 

 made in response to the remarks and suggestions of 

 critics and friends, to whom I take this opportunity of 

 expressing my obligation. 



F. O. BOWER. 



GLASGOW, April 1891. 



