326 



MORPHOLOG Y. 



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

 the surface. 



652- In the spring after flowering the pollen 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 place in other 

 plants examined, one of the 

 sperm 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 ranunculaceas, the buttercups, 

 These simple pistils bear a greater 



Fig. 387- 



Section of pistil of tril- 

 lium, showing position of 

 ovules (macrosporangia). 



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- 

 pound pistil of tril- 

 lium we find that 

 the infoldings of the 

 three pistils meet to 



Fig. 388. r 



Mandrake (Podo- ic- rm three partial 



phyllumpeltatum). nnft , ;t .; nncl wn i c h 



extend nearly to the center, dividing off three spaces. In these 

 spaces are the ovules which are attached to the infolded margins. 

 If we make cross sections of a pistil of the May-apple (podo- 



