256 



PRACTICAL COURSE IN BOTANY 



Fig. 308. — Cross section 

 of a pome : ;)/, placenta ; c, 

 carpels ; /, fibrovascular bun- 

 dles. 



and hollowed out with the caljrx sepals at the top. Cut a 

 cross section midway between the stem and the blossom end, 

 and make an enlarged sketch of it. Label the thin, papery 

 walls that inclose the seed, carpels. 

 How many of them are there, and how 

 many seeds does each contain ? The 

 carpels, together with all that portion 

 of the fruit which surrounds and ad- 

 heres to the ovary, constitute the peri- 

 carp, or wall of the seed vessel. The 

 fleshy part of the apple is no part of 

 the ovary proper, but consists merely 

 of the receptacle, or end of the foot- 

 stalk, which becomes greatly enlarged 

 and thickened in fruit. Look for a 

 ring of dots outside the carpels, connected (usually) by a 

 faint scalloped line. How many of these dots are there ? How 

 do they compare in number with the carpels ? With the rem- 

 nants of the sepals adhering to the blossom end of the fruit ? 



Next make a vertical section 

 through a fruit, and sketch, enlarg- 

 ing it sufficiently to show all the 

 parts distinctly. Observe the line of 

 woody fibers outside the carpels, in- 

 closing the core of the apple. Com- 

 pare this with your cross section ; to 

 what does it correspond ? Where do 

 these threads originate? Where do 

 they end ? Can you make out what 

 they are? (176.) Notice how and 

 where the stem is attached to the 

 fruit. Label the external portion of 



the stem, peduncle ; the upper part, from which the fibrovas- 

 cular bundles branch, the receptacle. It is the enlargement 

 of this which forms the fleshy part of the fruit. Try to find 

 out, with the aid of your lens and dissecting pins, the exact 



Fig. 369. — Vertical section 

 of a pome : p, peduncle ; /, 

 fibrovascular bundles ; s, seeds ; 

 pi, placenta ; c, carpel. 



