I INTRODUCTION. 
of the vascular cryptogams are arranged after that of ENGLER and PRranTt. 
Of the sp2cies and varieties mentioned in this volume, forty-five are proposed 
as new species and one is regarded as a new variety of a known species. 
One new genus, Diplocarex, has been proposed, and one family, Connaraces, 
and twelve genera are mentioned as new to the flora of Formosa. The latter 
genera are aS follows: — Rourea, COaucalis, Sium, COonioselinum, Beerlagioe- 
dendron, Amitostigma, Phyllomphax, Erythrodes, Thrixspermum, Ascocentrum, 
Holcoglossum, Trichoglottis. Thus, up to the present date, the flora of Formosa 
represents, so far as is known, 3,658 species and 79 varieties, belonging to 
1,197 genera and 170 families. 
The original plan of the work, as above stated, was that it should , 
completed in fifteen volumes, and I still intend, if circumstances permit, to 
publish five more volumes, issuing one each year. The completion of the 
study of the flora of Formosa, which is the real aim of this work, is son 
thing one cannot expect to accomplish even in a much longer time. For: 
present one can only hope that nothing will happen to interfere with the 
completion of the work as originally planned. For this all things seem to 
promise well. On the other hand there is always the. possibility of a chang 
in one’s personal circumstances, and it would be unfortunate if this work . 
which I have been engaged for a score of years should for any reason com. 
to an abrupt end and be left without having been given even a tentative form 
of completion. Such considerations have led me to think that I should avail 
myself of the opportunity presented by the publication of Volume X. to gi 
to it something of the formal character of a concluding number of the series. 1 
should then be quite satisfied to think that the work had been for. mally completed; 
even should the continuation of the latter part unfortunately be interrupted. 
_ Accordingly, Volume X. contains a general index to the series, from the 
first volume to the tenth, and also to the studies which I published while I 
was preparing this work on Icones. I have also added two papers, namely :— 
“ An interpretation of Gorrse’s Blatt in his ‘Metamorphose der Pflanzen ’, 
as an Explanation of the Principle of Natural Classification ” and “The Natural 
Classification of Plants, according to the Dynamic System”. The latter deals 
especially with the natural system established upon the principle on which, 
since my return from Tonkin in 1917, I have been reflecting, and refers 
generally to the explanation of natural classification to which my attention was 
