78 PISTIL. 



intinc projecting through the coat of the extine. By the sul- 

 phuric acid many tubes are projected from the same grain, 

 naturally only one or two. 



Raspail asserts that the pollen is a production of the internal 

 suit'ace of cells within the theca, to which the grains are attached 

 by a fuqicle. This is denied by other botanists. 



126. The color of pollen is generally yellow ; but it assumes 

 in different plants almost every color except green. The matter 

 contained within the pollen cells is called fovilla, which we be- 

 fore remarked consists of minute molecules, measuring, accord- 

 ing to Lindley, from the 4000th to the 30,000th of an inch in 

 length, and are of two kinds, one larger than the other. 



Pistil. 



127. The pistil, is the center of the flower, and forms the 

 summit of the axis of growth. It is, like the other floral organs, 

 a modification of the leaves. Each leaf of the pistil is called a 

 carpel. The pistil is divided into three parts, the germ (which 

 becomes the ovary), style, and stigma. 



The stigma (Fig. 127, c) is the summit of the 

 pistil, and is the extremity of the midrib of the leaf 

 which composes the pistil. It is the only part, ex- 

 cept the spongioles, that is not covered with the 

 epidermis. It is generally glutinous and moist, 

 thus causing the pollen grains to adhere to it, and 

 at the same time yielding enough moisture to make 

 them put forth the pollen tubes. It is covered with 

 papillae, which are undoubtedly the cells of the 

 parenchymous substance of which it is composed, 

 and is the channel^ through which, in all cases, the 

 fecundating matter is transmitted to the ovule. It 

 varies much inform; or if, with some botanists, we consider the 

 stigma only a surface fitted for the reception of the pollen and 

 transmission of the fertilizing substance, the variety of forms of 

 stigma usually described by botanists would properly come under 

 tie' style. Lindley remarks that nothing, properly speaking, is 

 a Btigma except the secreting surface of the style. This surface 

 is usually on the expanded summit of the style, but it frequently 

 occupies other situations. In the Iris it is a line on the back of 

 the trifid petal-like style; in some it occupies the side of the 



120. What is, the color of the. pollen grains! What is the fovilla?— 127. 

 "What La the pistill Into how many parts divided I What is each leaf thai 



composes it called ? What is the stigma ? With what is it covered ? 



