242 



PLANT LIFE. 



is divided into as many chambers as there are component 

 carpels, and the partition liy \x-hicli the cliamliers are sepa- 

 rated re[)resents the adjacent parts of the two carpels. Or 

 the carpels may unite with each other at their edges only, so 

 --|-^g— _-p-tT^ that the line of union is at the outside 

 ^^C;^3^^^^^ of the pistil. In this case the ovulary 

 will have a single chamber. In both these 



Fig. 252. — \ li-ans\'erse . , , , ^ 



section <,f the capsule .>f uicthods of union tlie normal numlicr of 



shepherd's purse. Tlie i 1 . t i ■ 1 



pistil consists of two chambers m the oviuary may be increased 



carpels, at whose united , - , 



edges two placenta; are by outgrowths fi-om the carpels them- 



formed carrying the 



ovules (now seeds 1. The sclvcs, as in figure 252, where from the 



partition from one pla- '" 



centato the other is an united edgcs ot the carpels a jjlate of tis- 



outgrowth (false parti- ^ 



tidn) and not part of the suc has growii oiit to meet a corrcsponcl- 



carpel. Magnified about 



6 diam.— After Bessey. ing One from the Other side, so that what 

 should be a one-chambered pistil has become two-chambered. 

 (Compare also fig. 276.) Even simple pistils are subject to 

 such subdivision of tlieir interior (fig. 253). 



■ -53 



Fig. 353, — L<iwer half of the I'istil of A^lrai:al!!S c.t >i<i,i\- nsis. It consists of i 

 carpel, Ijut is divided into two chambers by a false jiartition. an outgrowth f 

 midrib of the leaf. Magnified se\'eial diam. — After (.iray. 

 t^lG. 254. — Two stages in the de\'eloptnent of the o\ule of the currant ' ^ 

 longatudinal section of a young ovule; //.the sporangium; - ■' ' 



Fig. 



integument be 



longitudinal section ol a young ovule; //, the sporangium; //.inner integument be- 

 ginning to develop as a ring at base of // ; ///, the fundament of the outer integument ; 

 m, the mother cell of the megaspores; /)', a similar section of the siiorangium alone, 

 older, showing ///', ;//", ///"', the daughter cells of /// ; ///'", only becomes a perfect 



snore • ///' nnd iii" Hn not flevelon further and become tlestn ivcil ( 'ontent^ of n^lls 



oiuei, aiiowiijy /// , /'/ , "/ , tjit uciiij;iilci cciia oi " 



spore ; ///' and ///" do not develop further and becon 

 not shown. Magnified 350 diam. — After Warming. 



340. Ovules. — \n ovule consists of a megas[ioraiigium 

 partiall)' enveloped by one or two outgrowths tiom beneath. 



