PISTIL. 79 



pistil ; in others no point can be detected, by observation, that 

 corresponds in appearance to the stigmatic surface. The central 

 part of the stigma consists of a more lax tissue which leads di- 

 rectly to the ovary, and is called the conducting tissue. 



128. The style (Fig. 127, b) is a vascular organ, varying in 

 length, supported by the ovary, and supporting the stigma. It 

 is generally considered an unessential organ ; but Raspail says 

 that the style penetrates the ovary and becomes the placenta, 

 which would render its presence always necessary ; but this is 

 in opposition to all other botanists, so far as we know, the pla- 

 centa being considered the union of the edges of the folded 

 leaves composing the ovary. The style is sometimes articulated 

 to the summit of the ovary, and sometimes forms a continuation 

 of it. Although the style usually rises from the summit of the 

 ovary, yet in some cases it does not. In the Labiatce it comes 

 from the base, and in others from the side. These apparent 

 variations are produced by the unequal development of the parts 

 of the ovary ; one side being extended more than the other, 

 would, of course, turn the summit to the least developed side. 



12D. The ovary (Fig. 127, a) is the thickened base of the 

 pistil, and is that part of the organ containing the ovules, and 

 becomes the fruit in maturity, whatever may be its form. The 

 ovary, when the pistil is composed of a single leaf, is formed by 

 the folding of the leaf with the upper surface inward and united 

 by its edges, the lamina of the leaf forming the ovary. This 

 arrangement is well exhibited by the Peach. The furrow, which 

 is always seen running from the apex to the base of this fruit, 

 on one side, is the united margins. The midrib on the opposite 

 side is undistinguishable on the surface, but by dissection the 

 vessels will be found larger on that side, and running more di- 

 rectly from the base to the apex. 



13D. The placenta is the union of the two margins Fig - 128 - 

 of the carpels, and bears the ovules, which in maturity 

 become the seed. By carefully breaking the stone of 

 the Peach, we shall find the kernel attached to that 

 side of the cavity which corresponds to the depressed 

 line on the surface, showing that the kernel or nucleus 

 derived its origin and support from that side which is 

 formed by the margin of the leaf. The Cherry is an- 

 other example of a monocarpelous pistil. (Fig. 128.) 



131. Although, some plants, like those above noticed, „ 



, i • • «i * i * . • i Monocarpe- 



have their pistils ot one lear, yet in most cases they lous pistil. 



What is the conducting tissue ?— 128. What is the style?— 129. What 

 is the ovary ? How is it formed when the pistil is composed of a single 

 leaf? When exlibited? Explain the peach. — 130. What is the placenta? 



