THE STUDY OF TYPICAL FRUITS. 183 
(4) The central column or axis of white pithy tissue. 
(5) The location and attachment of any seeds that may be encountered 
in the section. 
Make a sketch to illustrate these points, comparing it with Fig. 181. 
Study the section with the magnifying glass and note the little spherical 
reservoirs near the outer part of the skin, which contain the oil of lemon 
which gives to lemon-peel its characteristic smell and taste. Cut with 
the razor a thin slice from the surface of the lemon-peel, some distance 
below the section, and at once examine the freshly cut surface with a 
magnifying glass to see the reservoirs, still containing oil, which, how- 
ever, soon evaporates. On the cut surface of the pulp (in the original 
cross-section) note the tubes in which the juice is contained. These 
tubes are not cells, but their walls are built of cells. Cut a fresh section 
across the lemon, about midway of its length and sketch it, bringing out 
the same points which were shown in the previous one. The fact that 
the number of ovary cells in the fruit corresponds with the number of 
minute knobs in the depression at its base is due to the fact that these 
knobs mark the points at which fibro-vascular bundles passed from the 
peduncle into the cells of the fruit, carrying the sap by which the growth 
of the latter was maintained. 
Note the toughness and thickness of the seed-coats. Taste the kernel 
of the seed. 
Cut a very thin slice from the surface of the skin, mount in water, 
and examine with a medium power of the microscope. Sketch the 
cellular structure shown and compare it with the sketch of the corky 
layer of the bark of the potato tuber. 
Of what use to the fruit is a corky layer in the skin? (See § 250 for 
further questions. ) 
216. A Legume, the Bean-Pod.1— Lay the pod flat on the table and 
make a sketch of it, about natural size. Label stigma, style, ovary, calyz, 
peduncle. 
Make a longitudinal section of the pod, at right angles to the plane in 
which it lay as first sketched, and make a sketch of the section, showing 
the partially developed seeds, the cavities in which they lie, and the solid 
portion of the pod between each bean and the next. 
Split another pod, so as to leave all the beans lying undisturbed on 
one-half of it and sketch that half, showing the beans lying in their 
-1 Any species of bean (Phaseolus) will answer for this study. Specimens in the 
condition known at the markets as ‘‘shell-beans” would be best, but these are not 
obtainable in spring. Ordinary “‘string-beans” will do. 
