TriE FLOn'Jili 



107 



rather leaflike. Each fertile scale bears on its upper sur- 

 face near the base a pair of ovules, lu such llowei's the 

 pistils, therefore, are not closed, aud the seed throughout 

 its history is naked, i.e. exposed. Accordingl}^, the cone- 

 bearing trees and their relatives are designated as Gymno- 

 SPEi'.Jis (naked seeded). 



200. The corresponding term for plants with closed 

 ovaries is AN(!i()si>Ei;.i\i,s. Angiospernious Ihjwers will )jc 

 meant in this chapter unless otherwise stated. 



201. The stigma has been described as a detiuite portion 

 of the surface of the style, or, when the style is lacking, 

 of the ovary. When the tip of the st)de is enlarged in 

 a knob, or branched, or finely dissected in a plume ( Fig. 

 166), it is convenient to speak of the whole organ — and 

 not merely the surface — as tlie stigma. 



Under the lens and even to the naked eye tlie stigmatic 

 surface is distinguished by a granular texture aud often 

 by a viscid secretion, designed to secure the pollen grains 

 which fall upon it or are brought to it. 



202. For the ovules are not the sole conce[)tacles of 

 racial life as it is passed onward from one generation to 

 tlie next. Other and simpler bodies produced in the 

 flower are equally freighted with inheritance, namely, the 

 individual pollen grains, emitted in multitudes as yellow 

 dust by the floral or- 

 gans standing around 

 the pistil or pistils. 

 Each " grain " viewed 

 through the microscope 

 is seen to 1)6 a spherical 

 liody (Fig. 166) — in 

 many cases, however, elongated or otherwise modified — 

 of the simplest description as regards structure. It con- 

 sists of a minute portion of living substance of jellylike 

 consistency, surrounded by a tough elastic coat or wall. 

 As will shortly be seen, this body is capable of growth, 

 and plays an equally important part wdth the ovule in the 

 reproduction of plants. 



\;inous forms of pollen, inai^iiilied, 

 illustrn ling the maiiniT in which the 

 "wall is sculptured in dilferent species 

 of plants. 



