[9-49 
It will, perhaps; appear probable, 
that one of the great laboratories of 
nature for cleanfing and purifying 
‘the air of our atmofpheré is placed 
in the -fubftance of the leaves, and 
put in action by the influence of the 
light; and that the air thus purified, 
but in this itate crown utelefs or 
noxious to the plant, is thrown out 
for the greateit part by the excre- 
tory-ducts, placed chiefly, at leait in 
far the mott part of -plaats, on the 
under fide of the leaf. 
els. chore: not ae ili yt a 
_the under part “of the leaves 
have been cl hiely ¢ defined for i 
—purpote.-becaufe. in. this. -way.the- 
eepeaesiitated airy fats. conti- | 
“mually out of this furface, is inclined 
“to fatk ‘Father down wards; aS a. bene- 
ficial fhower for ‘he ule of the ani- 
~mals who all breathe i ina ate = of 
as 
