14 PRACTICAL COURSE IN BOTANY 
12. Dissection of a bean. — Sketch a dry bean as it lies in 
the pod, showing its point of attachment and any markings 
that may appear on its surface. Then take it from the pod and 
examine the narrow edge by which it was attached. Notice 
the rather large scar (commonly called the eye of the bean) 
where it broke away from the point of 
attachment. This is the hilum. Near the 
hilum, look for a minute round pore like 
a pinhole. This is called the micropyle, 
from a Greek word meaning “a, little 
gate,” because it is the entrance to the 
interior of the seed coat. There was no 
Fics. 17, 18.—A kid-  micropyle observed in the corn grain, 
ney bean: 17, side view; Se ad < 
18, front view, showingh, because it is not a true seed but a fruit 
Hh; CesT inclosing a single seed. The inclosing 
membrane is the fruit skin, which has become incorporated 
with the seed coat and taken its place as a protective covering. 
Compare a soaked bean with a dry one; what difference do 
you perceive? How do you account for the change in size and 
hardness? Find the hilum and the micropyle in the soaked 
bean. Lay it on one side and sketch, with the micropyle on 
top; then turn toward you the narrow edge that 
was attached to the pod and sketch, labeling all 
the parts. Make asection through the long diam- 
eter at right angles to the flat sides, press it 
slightly open, and sketch it. Notice the line or 
slit that seems to cut the section in half longitu- 
dinally, and the small round object between the 2 
halves at one end; can you tell what it is? re a ar 
Slip off the coat from a whole bean and notice its 4 bean, show- 
texture. Hold it up to the light and see if itshows ee 
any signs of veining. See whether the scar at the hilum extends 
through the kernel, or marks only the seed coat. Lay open the 
two flat bodies into which the kernel divides when stripped of 
its coats, keeping them side by side, with the part above the 
micropyle toward the top. Sketch their inner face and label 
