40 Principles of Plant Culture. 
58. Chlorophyll (chlo’-ro-phyll). Soon after the plant- 
let emerges from the seed-case, a green color appears in the 
parts most exposed to light. This green color is due to the 
formation within the cells of a substance known as chloro- 
phyll— the green coloring matter of plants. Chlorophyll 
forms only in the light, and when a plant containing green 
leaves is kept for a time in the dark, as when celery is 
banked up with earth, the chlorophyll disappears, and the 
green parts become white. The chlorophyll saturates defi- 
nite particles of the protoplasm, called chlorophyll bodies, 
and since the cell-walls and protoplasm are transparent, in the 
younger cells, the chlorophyll bodies give the parts contain- 
Fic. 13. Showing cross section through leaf of Fagus sylvatica. Ch, chloro- 
phyll bodies; Ep, epidermis of upper surface of leaf; Ep”, epidermis of lower sur- 
face; K, cells containing crystals; P’, palisade layer; F, vascular bundle; S, 
stoma; J, spaces between the cells, (intercellular spaces). Highly magnified. 
{After Strasburger). 
ing them a green color. Fig. 13 shows the distribution of 
the chlorophyll bodies in the cells of a portion of the leaf 
of the beech. They appear as minute globules, which in 
this case, are mostly located near the cell-walls. It will be 
seen that they are most numerous near the upper surface of 
the leaf,— the part most exposed to the sun’s rays. 
