140 ELEMENTS OF BOTANY. 



top, the three lobes of the stigma. Make a sketch of these parts ahout 

 twice the natural size, and label them. Touch a small camel's-hair pencil 

 to one of the anthers, and then transfer the pollen thus removed to the 

 stigma. This operation is merely an imitation of the work done by insects 

 which visit the flowers out of doors. Note how readily the pollen clings 

 to the rough stigmatio surface. Examine this adhering pollen with the 

 two-inch objective, and sketch a few grains of it, together with the bit of 

 the stigma to which it clings. Compare this drawing with Fig. 140. Make 

 a cro.ss-section of the ovary about midway of its length, and sketch the 

 section as seen through the magnifying glass. Label the three chambers 

 shown, ceils of the ovary,^ and the white egg-shaped objects withm, 

 ovules.'^ 



Make a longitudinal section of another ovary, taking pains to secure • 

 a good view of the ovules, and sketch as seen through the magnifying 

 glass. 



Mailing use of the information already gained and the cross-section of 

 the ovary as sketched, construct a diagram of a cross-section of the entire 

 flower on the same general plan as those shown in Fig. 135.^ 



Split a flower lengthwise,* and construct a longitudinal section of the 

 entire flower on the plan of those shown in Fig. 133, but showing the 

 contents of the ovary. 



1 74. The Flower of the Buttercup. — Make a diagram of the mature 

 flower as seen in a side view, looking a little down into it. Label the five 

 pale greenish yellow, hairy, outermost parts sepals, and the five ^ larger 

 bright yellow parts above and within these petals, and the yellow-knobbed 

 parts which occupy a good deal of the interior of the flower, stamens. 



Note the difference in the position of the sepals of a newly opened 

 flower and that of the sepals about a flower which has opened as widely 

 as possible. Note the way in which the petals alternate with the sepals, 

 i.e., each petal springs from a point just above the space between two 

 sepals. In an opening flower, observe the arrangement of the edges of 

 the petals, two entirely outside the others, two entirely inside, one with 

 one edge in and the other out. 



Cut ofi a sepal and a petal, each close to its attachment to the flower ; 



1 Notice that the -word cell here means a comparatively large cavity, and is not 

 used in the same sense in which we speak of a wood cell or a pith cell. 



2 The section will be more satisfactory if made from an older flower, grown out of 

 doors, from which the perifinth has fallen. 



3 Consult also the footnote on p. 138. 



* One will do for an entire division of the class. 

 ^ Sometimes more. 



