CHAPTER IV. 
STRUCTURE. 
HERE is so much of stability and 
YA permanence in the qualities which 
distinguish Trees from other and 
more fragile kinds of vegetation 
that especial interest must attach 
to inquiries concerning their 
structure. The whole subject relating 
to the structure of plants is indeed ex- 
ceedingly interesting to the student of 
Nature. But perhaps for the general reader, as 
that expression is usually understood, herbaceous 
plants—plants, we mean in this sense, that die 
down to their roots each year—have not quite 
the attraction which strongly induces investiga- 
tion concerning the chemical substances of which 
D2 
