VI 
PREFACE. 
which vegetables are constructed, or to the external 
appearance their elementary organs assume in a state 
of combination. It is exceedingly desirable that 
these topics should be well understood, because they 
form the basis of all other parts of the science. In 
physiology, every function is executed through the 
agency of the organs : systematic arrangements de- 
pend upon characters arising out of their consider- 
ation ; and descriptive Botany can have no logical 
precision until the principles of Organography are 
exactly settled. A difference of opinion exists among 
the most distinguished botanists, upon some points 
connected with this subject, so that it has been found 
expedient to enter occasionally into much detail, for 
the purpose of satisfying the student of the accuracy 
of the facts and reasonings upon which he is expected 
to rely. 
To this succeeds Vegetable Physiology (Book 
II.) ; or the History of the vital phenomena that 
have been observed both in plants in general, and in 
particular species, and also in each of their organs 
taken separately. It is that part of the science which 
has the most direct bearing upon practical objects. 
Its laws, however, are either unintelligible, or sus- 
ceptible of no exact appreciation, without a previous 
acquaintance with the more important details of Or- 
ganography. Much of the subject is at present in- 
volved in doubt, and the accuracy of some of the 
conclusions of physiologists is inferred rather than 
demonstrated ; so that it has been found essential 
that the grounds of the more popularly received 
opinions, whether admitted as true or rejected as 
erroneous, should be given at length. 
Next follows Glossology (Book III.); or, as 
it was formerly called. Terminology ; restricteil 
