}'ECE7\4TJJ-E KEl'RODUCTION. 23" 



iiK hide both sorts of si)Oro|)hylls. The pcriaiilh ma\' be eoni- 

 jjosed oi one or two kinds of len\es, oflen bright-colored. If 

 there are two sorts, those next the sporophylls are generally 

 highly colored, and constitute the ciiru//a. Each leaf of the 

 corolla, when distinct, is a />c/ii/. The lea\'es below the co- 

 rolla are often green. 'I'hey constitute the Cti/v.v, anil each, 

 when distinct, is a sc/hi/. 



331. Carpels. — The leaves (sporophylls) bearing the 

 ovules (^niegasporangia ) are called carpels. They nia)- be 

 llattened ; or so carved that in the course of their de\elop- 

 nient the edges unite and a ca\ itv is more or less periectlv 

 enclosed ; or neighboring carpels mi\y grow together in such 

 a way as to form a case. Siu h hollow structures, whether 

 composed of one or more carjiels, are often somewhat jjestle- 

 shaped, whence they early receix'ed the name /■/>//'/ (fig. 244). 

 A flower whose only essential organs are jiistils is called pi's- 

 lillalc. The sporangia arise usuallv upon the x'entral (inner) 

 face or the edges of the carpels. In the open carpel the)' are 

 e-xjiosed, but in the closed carpels they are completely shut 

 in, excejit for a narrow opening which sometimes remains, by 

 which the interior cavitv eonmumicates with the outside air. 



332. Ovules. — Among seed plants the sporangia which the 

 carpels bear are nni\'ersally known as ovules, a name gix'en to 

 them mider the supposition that thcv were the eggs which, 

 upon fertilization, produce new plants. Though the}' are not 

 in any respect comp")arable to the real eggs (since thev are 

 produced bv the non-sexual or sjjorophyte phase), the name 

 is retained tor convenience. 



333. Gymnosperms and angiosperms. — When the changes 

 through which the o\ule passes are complete, it becomes the 

 seed, ^\'hen the o\'ules are produced \\\)0\\ the free surface of 

 an open carpel, the seeds are, therefore, exposed. (,)n the 

 contrarv, when the on'uIcs are borne within a closed pistil 

 (formed by one or more carpels) the seeds are cie\eloped 



