268 The Sex and Generative Organs of Plants, 



The ovum, however, is a product of that leaf of the flower, 

 which has arisen in an entirely different way from the 

 stamen, by a transformation of the common leaf, and which 

 is described as the pistil or female organ. By this transfor- 

 mation, the sheath (vagina) of the green leaf becomes the 

 ovarium, or germen. The midrib becomes the style, and the 

 broad part or lamina, which is of the whole comparatively 

 the most drawn together and changed, becomes the stigma. 

 The pistil generally assumes the middle place in the flower, 

 and completes the very wonderful palace of fhe plant. It 

 is now in the ovaria that the ova develop themselves. 

 They are generally found near the edge of the vaginal 

 part, which we must imagine to ourselves as rolled toge- 

 ther inwards, and grown together at its edges along its 

 whole length, so that thereby a cavity is produced in which 

 the ova are situated. This cavity either lengthens itself 

 upwards through the equally hollow style towards the 

 stigma, or it is here shut in by a fine cellular net which fills 

 up the middle of the style. 



The stigma, the highest part of the pistil, appears in most 

 cases in a form which differs materially from the broad por- 

 tion of a leaf, of which it must be regarded as a transforma- 

 tion. It is comparatively the smallest part of the pistil, 

 often looks like a round little knot, and is commonly formed 

 of cells closely packed on each other, without any distinct 

 skin over the surface. The ova which are formed in the 

 cavity of the ovaria, appear at first as very tender conical 

 warts, and consist only of cellular tissue without vessels. 

 We can, however, distinguish in them even before fecunda- 

 tion a cell, which is remarkable among the other ones by 

 its size and shape. This is the so-called embryo sac. The 

 ova themselves are called in this earliest stage the ovules. 

 At their base, that is, where these little cellular warts issue 

 from the pistil, there appear early one or two swollen looking 

 rings, which by degrees lengthen themselves out in the 



