Since its first appearance in 1884, Professor Haberlandt's Physiologische Pflanzenanatomie has undergone revision and amplification on three successive occasions. In its present form, therefore, this work may be assumed to embody the mature and considered views of its author, with regard to that section of botanical science which he has made peculiarly his own.<br><br>In order to retain, as far as possible, the fluency which is a prominent and agreeable feature of the original text, I have not scrupled to translate with some freedom, where necessary; at the same time, I have taken every care to ensure that the author's meaning should be faithfully reproduced throughout. The limited number of words and phrases for the insertion of which I am personally responsible, - for example the term photosynthesis on p.262 - are distinguished by being enclosed within square brackets.<br><br>I desire to record my indebtedness to my wife for assistance in proof-revision and in the compilation of the indices, and to Professor F.0. Bower, Sc.D., F.E.S., for much helpful advice and encouragement.