380 PISTIL AND OVARY. PART n. 



after expulsion even in pollen taken from dried speci- 

 mens. After the liquid ceases to circulate, it becomes 

 concentrated and contracted ; and when the pollen is 

 only enclosed in one delicate membrane, it simply bursts 

 the vesicle ; but, as most pollen grains have a double 

 coat, they burst open at the slits, or pores, on their 

 surface, and through these the internal membrane, in 

 the form of a tube, is protruded, and emits its contents ; 

 but it may be projected to a considerable distance with- 

 out bursting. 



The pistil in a very young state is a greenish concave 

 body scarcely to be distinguished from a nascent leaf; it 

 becomes more concave ; and finally the borders meet and 

 unite, so that a hollow body is formed, which ultimately 

 becomes a perfect pistil consisting of three parts, the 

 apex or stigma, the style, and the ovary, in which the 

 ovules, or unripe seeds, are formed and fertilized, the 

 latter afterwards becoming the fruit. 



The ovary is composed of an outward skin contain- 

 ing cellular tissue and vascular bundles of spiral vessels, 

 which, running upwards, converge towards the style ; 

 they vary in number, and are sometimes ramified. A 

 single ovule, which is an unripe seed, may be produced 

 within the ovary, or the ovary may be divided into two 

 or more compartments, in each of which an ovule may 

 be formed and attached to the ovary by a mass of cel- 

 lular tissue, and not unfrequently by a single thread. 



The style, when examined with a microscope, is a 

 hollow tube, or canal, extending from the cavity of the 

 ovary to the stigma. It consists of cellular tissue with 

 vascular bundles near the circumference, which pass 

 upwards in straight lines, and end below the summit. 

 In certain cases the canal is open ; in others it is ob- 

 structed by lax cellular tissue having many gaps. The 

 stigma is an expansion of that lax tissue at the point 

 where the canal opens externally. At the time of fruc- 



