.30 
NATURAL SYSTEM. 
‘ Thirdly^ in the closenesse of it; for, 
though all the microscopical pores of the 
wood were very conspicuous in one position, 
yet by altering that position of the polish’d 
surface to the light, it also was manifest 
that those pores appear’d darker than the 
rest of the body, onely because they were 
fill’d up with a more dusky substance, and 
not because they were hollow.” 
The most obvious divisions which obtain 
in the vegetable kingdom, are those which 
are manifested in exterual form. The clas¬ 
sification, called the natural system, reckons 
about two hundred and seventy two families 
or tribes. A specimen of one or two of 
these will suffice to shew the characters 
usually relied on to serve as the basis of the 
leading divisions. 
The heath tribe for instance, comprising 
the well known ornamental erica, rhododen¬ 
dron, azalea, and other forms, all evergreen 
shrubs, having a uniform resemblance in the 
number and position of their organs, and a 
common character and habit of growth, 
flourishing mostly in southern Africa and 
almost unknown in Australia. 
