2 ec ae 
the light of the fun, the firft ready 
to operate; when thofe of the op- 
pofite fide of the tree, fhaded by the 
firft, were ftill in their ftate of 
{tupor. 4 
A ready way to know this time 
exactly is to put a leaf or two, from 
the plant you are to éxamine in 
this refpect, in a elafs full of frefh 
pump-water, and to obferve, whe- 
ther the bubbles appear upon them 
about as quick as they ufe to 
do in the full day time. If they do, 
you may be fure they are fit for 
the bufinefs. 
But there is a readier way to 
know exactly this article of time, 
which I found by the water in the 
jar in which the green matter, dif- 
covered by Dr. Prieftley, is already 
formed. The doctor found that | : 
this green matter yieligs air bubbles 
ee = ; only 
