THE ESSENTIAL OilGANS. 



45 



lower becomes the outer surface of the ovary. By this arrange- 

 ment two sutures or seams will be formed the dorsal, at the 

 back, by the midvein ; the ventral, in front, by the joined mar- 

 gins of the leaf. This view of the pistil is remarkably confirmed 

 and illustrated by the flowers of the Double Cherry (124, 125), 

 where the pistil may be seen in every degree of transition, re- 

 verting toward the form of a leaf. This carpellary leaf stands 

 in the place of the pistil, having the edges infolded toward each 

 other, the midvein prolonged and dilated at the apex, as shown 

 in 125. 



118 



L\ 121 



I/ 123 



117, Simple pistil of Strawberry, the style lateral. 118, Simple pistil of Crowfoot, cut to show the 

 ovule. 119, Simple pistil of the Cherrv. 120, Vertical section showing the oviile (o), style (.<), stigma 

 (a). 121, Cross. section of the same. 122, Compound pistil of Spring-beauty. 123, Cross-section of the 

 tame, showinjr the 3 clls of the ovary. 124, Expanded carpellary leaf of the Double Cherry. 125, The 

 same partly folded, as if to form a pistil. 



127. The placentae are usually prominent lines or ridges 

 extending along the ventral suture within the cell of the ovary, 

 and bearing the ovules. They are developed at each of the two 

 edges of the carpellary leaf, and are consequently closely parallel 

 when those edges are united, forming one double placenta in the 

 cell of each ovary. 



128. The simple carpel, with all its parts, is completely exemplified in the Pea-pod. 

 When this is laid open at the ventral suture, the leaf form becomes manifest, with the 

 peas (ovules) arranged in an alternate order along each margin, so as to form but one row 

 when the pod is closed. In the pod of Columbine (127), the ovules form two distinct 

 rows , in the simple Plum carpel, each margin bears a single ovule ; and in the one-ovuled 

 Cherry, only one of the margins is fruitful. 



129. The stigma is the glandular orifice of the ovary, communi- 

 cating with it either directly or through the tubiform style. It 

 is usually globular and terminal, often linear and lateral, but 

 subject to great variations in form. It is sometimes double or 

 halved, or 2-lobed, even when belonging to a single carpel or to 



