LUTHER BURBANK 



The pollen grain effects union with the ovule 

 by sending out a thread-like filament of proto- 

 plasm, like a tiny root, which penetrates the 

 stigmatic surface, passes down along through the 

 style, and carries the nucleus of the pollen grain 

 to the nucleus of an ovule. When the two 

 nuclei come in contact, fertilization has been 

 accomplished. 



When pistil and the stamens have been con- 

 sidered, we are through with the really essential 

 mechanisms of the flower. 



From the human standpoint, of course, chief 

 interest centers in the corolla with its wide- 

 spreading petals of varied colors. To the plant 

 itself this structure is in a sense essential, inas- 

 much as it supplies the visible signal that attracts 

 the attention of the insect. But beyond this it has 

 no share in the process of fecundation. We shall 

 have occasion to consider the form and structure 

 of this showy portion of the flower in a multitude 

 of individual cases, and to observe how it may be 

 modified by process of selection, but from the 

 present standpoint it does not call for further 

 consideration. 



From the standpoint of the pollenizer, the 

 stamens with their pollen-bearing anthers and the 

 receptive pistil — with or without a stigma at its 

 tip but always having one or more ovules in the 



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