OVULE. 



follow the same law of alternation, as is exhibited in Fig. 133, 

 in which a represents the axis, bb the whorl contiguous to it, 

 and c c the exterior whorl. 



134. in some cases the receptacle is either convex as in the 

 Strawberry (Fig. 134), or concave as in the Rose (Fig. 135). 



Fig. 134. 



Strawberry. 



Fig. 135. 



In the former case the outer series, a a, will be the lowermost 

 whorl, and in the latter, the upper whorl will be in reality the 

 lowermost in point of development, becoming the most elevated 

 contrary to its true position by the peculiar development of the 

 receptacle. 



135. The extremity of the axis, which supports the carpels 

 is called the receptacle. In some cases it is merely the end of 

 the flower-bearing branch without having undergone any modi- 

 fication ; at others, it is an expanded disk, and is called a torus. 

 When it rises from the basis of the calyx, bearing the stamens 

 as in the Magnolia, it is called Gynophore. When it is succu- 

 lent, bearing many ovaries as in the Strawberry, it is called 

 Polyphore. We have the Gynobase when a fleshy receptacle 

 has but a single row of carpels inclined towards the center. 



Ovule. 



136. The Ovule is the young grain, not having received the 

 influence of the pollen. If we take a flower-bud of the Poly- 

 gonum, and take the ovary and dissect it carefully, we find 

 situated in the bottom of the cavity a small conical body (Fig. 

 13G, 1, ti), which is called the nucleus. It is a homogeneous 



134. Explain the strawberry. The rose. — 135. AY hat is the receptacle * 

 Torus? Gynophore ? Polyphore? — 136. What is the ovule? Nucleus 1 

 Describe it. 



