vi 
PREFACE. 
I have begun with what is called Organography 
(Book I.) ; or an explanation of the exact structure of 
plants ; a branch of the subject which comprehends 
all that relates either to the various forms of tissue of 
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 without the principles of Organography 
are first 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 par- 
ticular 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 suscep- 
tible of no exact appreciation, without a previous 
acquaintance with the more important details of Or- 
ganography. Much of the subject is at present 
involved 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 
