4/6 THE BEAN PLANT. [CHAT. 



a. The large close-fitting cells, with irregularly- 

 wavy margins and no chlorophyll, which chiefly 

 make up the epidermis. 



p. The openings here and there in it {stomaia) ; 

 the two curved, chlorophyll-containing guard- 

 cells bounding each stoma. 



e. Gently pull a midrib in two across its long axis ; 

 note the fine threads uniting the two broken ends; 

 cut them off with a sharp pair of scissors, mount 

 in water and examine with } or J objective : they 

 will be found to consist of partially unrolled spiral 

 vessels. 



e. The flower. 



1 . Its general structure. 



a. Borne on a short stalk {peduncle). 



b. Composed of four rows or zvhorls of organs. 



a. The external green cup-like calyx. 



p. Inside the calyx the corolla: the most con- 

 spicuous part of the flower. 



y. Inside the corolla the stamens. 



8. Within the stamens i\\c pistil. 



2. The calyx. 



A cup terminated at its free edge by five prominent 

 points, two dorsal, and three ventral : the five small 

 midribs running along it (one to the end of each of 

 the points) represent the free ends of five sepals, 

 which are united below. 



3. T/ie corolla. 



a. Composed of five pieces or /r/<7A. 



a. On the dorsal side, a single large piece [vexil- 



