82 
MANUAL, OF NATURE STUDY. 
have some important work to do, or else it must 
contain in store something of infinite value to the 
plant; otherwise it would not go to the trouble of 
constructing these stomata through the epider¬ 
mis, thus making thoroughfares, or gateways, con¬ 
necting the inner green mass with the outside world. 
Why does the detached leaf wither when exposed 
to dry air or sunlight? Try the experiment to see 
that such a result is true. Why do corn leaves 
curl up during the heat of the day in dry weather, 
and open out again at night ? Invert a tumbler or 
glass fruit jar over a bunch of fresh leaves, and in 
a few minutes observe the moisture collected on 
the inside of the vessel. Where did the moisture 
come from? Can you now see any use for the 
pores of the epidermis? Why do plants look so 
bright and green after a warm spring rain ? Do 
the stomata have anything to do with it ? How ? 
We have already learned that root hairs draw 
moisture out of the soil, and with the moisture all 
dissolved substances, the water serving chiefly as a 
carrier, or vehicle, for conveying material to the aid 
of the seed factory. 
We also learned that the villi of our elementary 
canal opened their mouths just wide enough to 
drink the dissolved portion of our food, the water 
or liquid serving as a carrier for the food that could 
