[ 998 ] 
If there be any circulation in the winter, it is ex- 
ceedingly languid; but it is probable it does exift 
in fome {mall degree. 
9. Does any water perfpire through the bark of the 
tree, or from the leaves? . 
I do not think it does; perhaps we may except the 
young twigs, the bark of which may admit of ab- 
forption and evaporation. 
10. What is the effect of dew upon plants ; and to 
what extent is it favourable to vegetation? 
Perhaps it checks evaporation, favours fecretion, 
and by a grateful coolnefs invigorates. I have never 
underftood but its utility was univerfal, unlefs we 
except plants not naturalized to our climate. 
IV. CONCERNING LIGHT AND HEAT. 
1. What are the effects of light and heat, in promo- 
ting the growth of plants, and bringing them te 
perfection ? 
Fruits moft expofed to the fun are the fulleft co- 
loured and the richeft flavoured. Iconjefture, that 
light improves or produces colour, and heat the 
flavour. From the general direétion and appearance 
of trees, and their foliage, I think they are influenced 
by both; how that influence is exerted, is not eafily 
afcertained. 
2. Do you know of any plants raifed totally in dark 
places? Do they produce flowers or fruit in that 
Situation ? 
I have 
