280 Plant-Breeding 



or other fruit ; but it is not able to bear seeds until it is 

 assisted by the pollen. The pollen falls upon the roughish 

 or sticky surface of the stigma, and there germinates or 

 sends a minute tube downwards through the style and 

 finally reaches the ovule, which, when fertilized, rapidly 

 ripens into the seed. The nature of this fecundation is 

 not germane to the present subject ; but it may be said 

 that only one pollen-grain is necessary to the fertilization 

 of a single ovule, but the addition of a superabundance 

 of pollen greatly stimulates the growth of the fleshy or 

 enveloping parts of the fruit. It is important that the 

 person who desires to cross plants should become familiar 

 with the stigma when it is "ripe," receptive, or ready to 

 receive the pollen. This condition is usually indicated 

 by the glutinous or sticky or moist condition of the stigma, 

 or in those stigmas which are not glutinous it is told by 

 the appearing of a distinctly roughened or papillose 

 condition. This receptive condition generally occurs 

 about as soon as the flower opens. If pollen is withheld, 

 the stigma will remain receptive much longer than when 

 fertilization has taken place, in some flowers for two 

 or three days. 



The pollen is discharged from the anther in various 

 ways, but it most commonly escapes through a chink or 

 crack in the side of the anther. Sometimes it escapes 

 through pores at one end of the anther; and in other 

 cases there are more elaborate mechanisms to admit of 

 its discharge. In most plants, the anthers and stigma 

 in the same flower mature at different times, so that 

 close-fertilization or in-breeding is avoided. This is 

 well illustrated in the bellflower, Fig. 80. Here the anthers 



