64 



FRUITS 



I20. — Cross seciion of a pome : 

 pi, placenta ; c, carpels ; f, fibro- 

 vascular bundles. 



nature will be more apparent on comparing them with 

 a hip, which is clearly only the end of the footstalk 



enlarged and hollowed out with 

 the calyx sepals at the top. Cut 

 a cross section midway between 

 the stem and the blossom ends, 

 and sketch 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 taken 

 together constitute the pericarp, 

 or wall of the seed vessel. The 

 fleshy part of the apple is, strictly speaking, no part of 

 the seed vessel or ovary proper, but consists merely of the 

 receptacle, or end of the footstalk, which becomes greatly 

 enlarged and thickened in fruit. The word pericarp, how- 

 ever, is often taken in a broader sense, to include all that 

 portion of the fruit which surrounds and adheres to the 

 ovary, no matter what its nature or texture. 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 remnants of the sepals ad- 

 hering to the blossom end of 

 the fruit.? /- — ^W V 



75. Next make a vertical sec- 

 tion through a fruit, and sketch 

 it. Notice the line of woody 

 fibers outside the carpels, inclos- 

 ing the core of the apple. Com- 

 pare this with your cross section ; 

 to what does it correspond 1 

 Where do these threads origi- 

 nate .■■ Where do they end .' Can 

 you make out what they are .' (See Section 43 ; they are the 

 fibrovascular bundles that connected the veins in the petals 



121. — Vertical section of a 

 pome : p, peduncle ; /| fibrovas- 

 cular bundles; j, seeds; //, pla- 

 centa; (,, carpel. 



