PREFACE 
AutHoucH during recent years considerable additions have 
been made to our elementary botanical textbooks, not one 
has appeared which deals solely, or at any length, with the 
subject of vegetable physiology..?This has been either 
presented to the reader as a particular section in a com- 
prehensive work, or treated of incidentally in connection 
with anatomical detail. This is the more strange, as an 
adequate and intelligent appreciation of the forms and 
structure of vegetable organisms can only be gained by a 
consideration of the work they have to carry out. It must 
be evident to the student of Nature that the peculiarities 
of external and internal form, of which any particular plant 
has become possessed, have arisen necessarily in con- 
nection with the need of mechanisms to do certain work, 
to overcome particular disadvantages, and generally to 
bring the organism into a satisfactory relationship with the 
surroundings among which it finds itself. 
I have been led by these considerations to endeavour to 
fill this gap by writing an introduction to the subject, 
which, while putting physiology into its proper prominence 
among the branches of botanical study, shall serve to pave 
the way of the student and of the general reader to the 
more complete discussion of the subject which may be met 
with in the advanced textbooks of Sachs, Vines, and 
Pfeffer. 
