326 



MOKPHOLOG Y. 



of pear fruit, tfie latter being kept in a moist chamber to prevent drying 

 the surface. 



652. In the spring after flowering the pjollen escapes from the anther sacs, 

 and as a result of pollination is brought to rest on the stigma of the pistil. 

 Here it germinates, as we say, that is, it develops a long tube which makes 

 its way down through the 

 style, and in through, the 

 micropyle to the embryo sac, 

 where, in accordance with 

 what takes ]iiace in otlicr 

 plants examined, one of the 

 Sfierm cells unites with the 

 egg, and fertilization of the 

 egg is the result. 



653. Macrospore and embryo sac. 



three carpels are united into one, 

 two carpels are also united into one 

 Simple pistils are found in many 

 in the ranunculacex, the buttercups, 

 These simple pistils bear a greater 



-In trillium the 

 and in dentaria the 

 compound pistil. 

 plants, for example 

 columbine, etc. 

 resemblance to a 

 leaf, the margins of 

 which are folded 

 around so that they 

 meet and enclose 

 the ovules or spo- 

 rangia. 



654. If we cut 

 across the com- 

 jiound jnstil of tril- 

 lium we find that 

 the infoldings of the 

 three pistils meet to 

 form three jiartial 

 partitions which 

 extend ncarl)- to the center, dividing off three spaces. In these 

 spaces are the o\'ules which are attached to llie infolded margins. 

 If \vc make cross sections of a pistil of the jNIay-apple (podo- 



Fig. 3S-. 



Section of iiistil of tril- 

 lium, showing jiositionof 

 ovules (niacrosiiorangial. 



Fig. jSS. 

 Mandrake (Pudo- 

 phyllum peltatum). 



