MINUTE STRUCTURE OF LEAVES. 111 
How does the epidermis of the two leaves compare ? 
Which has the larger stomata ? 
Which would better withstand great heat and long drought ? 
138. Chlorophyll as found in the Leaf. — Slice off a little 
of the epidermis from some such soft, pulpy leaf as that of 
the common field sorrel,’ live-forever, or spinach ; scrape from 
the exposed portion a very 
httle of the green pulp; 
examine with the highest 
power attainable with 
your microscope, and 
sketch several cells. 
Notice that the green 
coloring matter is not uni- 
formly distributed, but 
that it is collected into lit- 
tle particles called chloro- 
phyll bodies (Figs. 96, 98) 
and 205, e. 
139. Woody Tissue in 
Leaves.— The veins of 
leaves consist of fibro-vas- ; 
cular bundles containing 
wood and vessels much Fic. 98. — A Stoma of Thyme. 
Like those of the stem of 7 Surfide rien; 2, Sentim; «epidermal 
the plant. Indeed, these chamber; ap, pulp-cells of the leaf with 
Gpsiiles-in tho leat aro towne otis, itarosinar ae 
continuous with those of 
the stem, and consist merely of portions of the latter, looking as 
if unraveled, which pass outward and upward from the stem 
into the leaf under the name of leaf-traces. These traverse the 
petiole often in a somewhat irregular fashion. It is now easy 
to see that the dots noted on the leaf-scars of the horse- 
1 Rumex acetosella. 
