[ XXXV ] 



which was fiopt during the darknefs 

 of the night ; that this operation of 

 the plants is more or lefs brifk in pro- 

 portion to the clearnefs of the day, 

 and the expojition of the plants more 

 or lefs adapted to receive the direcl 

 influence of that great luminary ; 

 that plants (haded by high buildings^ 

 or growing under a dark Jhade of 

 other plants, do not perform this 

 office, but, on the contrary, throw 

 out an air hurtful to animals, and 

 even contaminate the air which fur- 

 rounds them ; that this operation of 

 plants diminifhes towards the clofe of 

 the day, and ceafes entirely at fun-Jet ^ 

 except in a few plants, which continue 

 . this duty fomewhat longer than other 's; 

 that this office is not performed by 

 the whole plant, but only by the 

 leaves and the green Jlalks that fup- 

 port them ; that acrid, ill-fcented, 

 c 2 and 



