PREFACE TO THE SECOND ENGLISH 

 EDITION. 



ALTHOUGH anything like a complete revision of the text 

 has been impracticable, I have been enabled, through the 

 liberality of the Publishers, to make several considerable 

 and important additions both to the text and figures (mainly 

 derived from the Second Edition of the Botanisches Praktikum), 

 and the chapters upon " Vascular Bundles " and " Bacteria " 

 have been to some extent rewritten. ... I have likewise 

 made a few verbal and other corrections, and, after much 

 hesitation, have eliminated the square brackets wherever 

 this has been feasible. 



I have most heartily to thank many correspondents here, 

 in America, and elsewhere, for numerous notes, memoranda 

 and criticisms. Although I may not at present have been 

 able to make use of them, these suggestions will not be lost 

 sight of ; and, even should they never be used, I am none 

 the less grateful for the kindly spirit which has prompted 

 their transmission. 



W. H. 



1st August, 1889. 



