Green Leaves at Work 93 
numerous, as to give their hue to the whole leaf. 
These specks are chlorophyll bodies, and they are 
the cause of the rich and tender green in summer 
fields and woodlands. 
The closely-packed tissue of the upper side of 
the leaf contains many cells, and hence many 
chlorophyll bodies. 
But Nature has not economized space in the 
arrangement of the lower leaf-cells,—and where 
cells are comparatively scarce chlorophyll is scarce 
also. Hence, the under surfaces of leaves are often 
pale in hue. 
Chlorophyll is formed only under the direct light 
of the sun. Tender young leaves, which have 
been shut up under bud-scales in the dark, con- 
tain as yet but few of the useful little green 
grains. The sun has not yet given them their 
working outfit, so expanding foliage is seldom really 
green. The budding oaks are of a warm reddish- 
brown or gosling-gray, according to their species. 
The new leaves of the poplars are silvery, and 
those of the willows are almost golden. 
Even the vegetable garden, when things are be- 
ginning to wake there, is a symphony of delicate 
color. The very smallest carrot-leaves are yellow 
or golden brown, 
