THE STUDY OF TYPICAL FRUITS 183 



216. A Legume, the Bean-Pod.^ — Lay the pod flat on the table 

 and make a sketch of it, about natural size. Label stigma, style, 

 ovary, calyx, 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 natural position and the funiculus or stalk by which each is 

 attached to the placenta ; compare Fig. 146. 



Make a cross-section of another pod through one of the beans, 

 sketch the section, and label the placenta (formed by the united 

 edges of the pistil leaf) and the midrib of the pistil leaf. 



Break oS sections of the pod and determine, by observing where 

 the most stringy portions are found, where the fibro-vascular bundles 

 are most numerous. 



Examine some ripe pods of the preceding year,^ and notice where 

 the dehiscence, or splitting open of the pods, occurs, whether down 

 the placental edge, ventral suture, the other edge, dorsal suture, or 

 both. 



217. An Akene, the Fruit of Dock. — Hold in the forceps a ripe 

 fruit of any of the common kinds of tlock,^ and examine with the 

 magnifying glass. Xote the three dry, veiny, membranaceous sepals 

 by which the fruit is enclosed. On the outside of one or more of 

 the sepals is found a tubercle or thickened appendage which looks 

 like a little seed or grain. Cut off the tubercles from several of the 

 fruits, put these, with some uninjured ones, to float in a pan of 

 water, and watch their behavior for several hours. What is appar- 

 ently the use of the tubercle? 



1 Any species of beau (Phaseolus) will answer for this study. Specimens 

 in the condition known at the markets as "shell-beans" would be best, but 

 these may not be obtainable in spring. Ordinary " string-beans " will do. 



2 Which may be passed round for that purpose. They should have been 

 saved and dried the preceding autumn. 



8 Rumex crispus, E. obtusifoliits, or E. veriicillatus. This should have 

 been gathered and dried the preceding summer. 



