PLANT ORGANS AND ORGANISMS 
I 7 I 
tary root, with its tip covered by a root cap. Continuous with the 
root cap is a root sheath or coleorhiza. The cotyledon or seed leaf 
consists of two parts: the scutellum which lies next to the endosperm, 
and is an organ of absorption ; and the sheathing portion which sur- 
rounds and protects the rest of the embryo. 
The embryo contains oil and proteids, but no starch. 
If a similar longitudinal section of a soaked grain be mounted in 
dilute iodine solution, the contents of the aleurone cells will be col- 
ored yellow indicating their proteid nature, while the starch grains 
will take on a blue to violet coloration. The endosperm will be 
observed taking up most of the room within the seed coat. The con- 
tents of its cells are not baled out to the embryo until after germina- 
tion begins. Indian Corn is therefore an albuminous seed. 
A MONOCOTYL SEEDLING 
Germination. — When any viable seed is planted in suitable soil, and 
furnished with oxygen and water and a certain degree of heat, ger- 
mination takes place. In the presence of moisture, etc., the seed 
swells, the ferments present within the cells of the endosperm then 
change the insoluble proteid, starch, and oil to soluble materials, 
which, in the case of Indian Corn, are absorbed in solution by the 
scutellum which bales this nourishment out to other parts of the 
growing embryo, there to be used in part in constructing new tissues, 
and in part to be consumed by oxidation or respiration. The process 
of respiration or breathing takes place when the plant takes in oxy- 
gen and gives off carbon dioxide. The oxygen oxidizes the tissues 
with an accompanying release of energy, which latter is necessary to 
life and growth. 
The combined pericarp and spermoderm bursts opposite the tip of 
the radicle, and the radicle, piercing through the cotyledonary sheath, 
protrudes. The cleft in the coat lengthens to the point opposite the 
tip of the plumule, which also protrudes after bursting through the 
cotyledonary sheath. The radicle, next, grows downward into the 
soil forming the primary root, and develops upon itself secondary or 
lateral roots, all of which give rise to root-hairs just above their root 
caps. Additional lateral roots emerge above the scutellar region 
