THE CASTOR BEAN 



121 



easy to perceive this condition in the pistil and to determine 

 the number of carpels of which it is made. The pistil shown 

 at Figure 63 B is evidently made up of three carpels, with 

 fused ovaries, but remaining more or less separated from 

 each other above. In some cases the style and stigmas, as 

 well as the ovaries, are fused together, and it is more diffi- 

 cult to determine the number; but even in these cases we 

 can easily distinguish in a compound pistil the number of car- 

 pels of which it is composed, by counting the number of rows 

 of seeds in the ovary, there being usually one row of seeds 

 for each of the carpels in the compound ovary. 



In some flowers the carpels are entirely absent, and such a 

 flower is called an imperfect flower. A perfect flower is a 

 flower that has both sta- 

 mens and pistils, and such 

 a flower is capable of pro- 

 ducing seeds. An imper- 

 fect flower is one in which 

 either the stamens or the 

 carpels are lacking, and 

 such flowers are not alone 

 capable of producing 

 seeds. 



Within the ovary are 

 found the true reproduc- 

 tive bodies. These at first 

 appear as several rounded 

 masses called ovules (Fig. 

 64), within each of which 

 is a single minute spore 

 cell, s, corresponding to 

 "the spores which form the 

 pollen. This spore never 

 leaves the ovule, but undergoes a series of changes within 

 the ovary which result in the production in each ovule of 



FlG. 64. A LONGITUDINAL SECTION OF 

 A PISTIL IN DIFFERENT STAGES OF 

 DEVELOPMENT 



A, showing the immature ovules with the en- 

 closed spore, s; B, the older ovules, containing an 

 egg, e; C, the ripened ovary with the seeds, sd, 

 each containing a young embryo plant. 



