THE SEED 13 
portion, endosperm, the depression near the center, embryo, or 
germ. 
Next take a grain that has been soaked for twenty-four 
hours. What changes do you see? How do you account for 
the swelling of the embryo? Remove the skin and observe 
its texture. Make an enlarged sketch of a grain on the 
grooved side with the coat removed, labeling the flat oval body 
embedded in the endosperm, cotyledon; the upper end of the 
little budlike body embedded in the cotyledon, plumule, the 
lower part, hypocotyl — words 
meaning, respectively, ‘‘ seed 
leaf,” “little bud,’ and 
“the part under the cotyle- 
don.” As this part has not 
yet differentiated into root 14 ns 
and stem, we cannot call it Fies. 14-16.— Dissection of a grain of 
F corn: 14, soaked grain, seen flatwise, cut 
by either of these names. away a little and slightly enlarged, so as to 
The cotyledon, hypocotyl, show the embryo lying in the endosperm ; 
15, in- profile section, dividing the grain 
and plumule together cOM- through the embryo and cotyledon ; 16, the 
pose theembryo. Pick out gubyotsken outwhole, The thick mas 
the embryo and sketch as upwards, the plumule ; the short projection 
it appears un ak hie- Tene. at the base, the hypocotyl (after Gray). 
Crush it on a piece of white paper; what does it contain? 
Make a vertical section of another soaked grain at ritht 
angles to its broader face, and sketch, labeling the parts as 
they appear in profile. Make a cross section through the 
middle of another grain and sketch, labeling the parts as be- 
fore. What proportion of the grain is endosperm and what 
embryo? Put a drop of iodine and of nitric acid separately 
on pieces of the endosperm, and note the effects. Test the 
seed coats and the cotyledon to see if they contain any starch. 
Notice that the corn grain has but one cotyledon, hence 
such seeds are said tc be monocotyledonous, or one-cotyledoned. 
The grains are not typical seeds, but are selected for examina- 
tion because they are large and easy to handle, can be ob- 
tained everywhere, and germinate readily. 
