504.  — ~ Experiments <9 Obfervations 
the veffel, and a thick covering of cement was 
applied after the glafs had been made dry with 
a cloth. Thefe precautions were ufed with a view 
to intercept all communication with the exter- 
nal air. The bottle was then expofed to the light 
in an inverted pofition, fo that the extremity of 
the flip was in the water, and its top remained 
in the inclofed gas. The leaves began to wither 
in a few days, and a number of frefh fhoots 
appeared in their places, both under the water 
and above its furface, before the tenth, which 
were green and clothed with leaves. . This 
experiment appears to prove clearly that parts, 
which are in a condition to grow. without the 
help of refpirable air, can give a green color 
to fuch frefh fprouts as they may chance. to 
produce when feparated from the atmofphere, 
provided the Jight thine on them. . We valfo 
know that the functions of vegetables are. but 
imperfectly performed during the fun’s ab- 
fence. They perfpire, upon an average, ten 
times more in twelve hours of day, than in.an 
equal fpace of night. When expofed to a,mo- 
derate light, they difcharge oxygene freely ; this 
procefs ceafes as foon as they are removed into 
the dark. Many herbs fold up their leaves at 
fun-fet, clofe their bloffoms, and experience a 
kind of torpor analogous to the fleep of animals, 
during which their internal ceconomy is. fuf- 
pended. 
