NOTE TO THE FIFTH EDITION. 



ONCE more the book has beeii revised throughout, where 

 the progress of the science appeared to render it necessary. 

 I may call attention especially to the notice of Mr. 

 Gwynne-Vaughan's discovery of the true nature of the 

 so-called tracheides of Ferns (p. 47) ; to the recognition 

 of the rnonoecism of Funaria (p. 132), a point to which 

 my attention was first called by the late Prof. Charles 

 Stewart, F.K.S., and to the mention of Mr. V. H. 

 Blackman's observations on the sexuality of the Bust 

 Fungi (p. 263). The concluding chapter, especially, has 

 needed a good deal of revision, and I have here intro- 

 duced a few words on recent remarkable observations on 

 Microcycas, the most cryptogamic of the living Seed- 

 plants. Two fresh illustrations of Bacteria, from 

 Fischer's Vorlesungen, have been introduced (Figs. 

 109 and 111 A). 



D. H. SCOTT. 

 October 11, 1907. 



