104 PEOPAGATIOS- OF PLANTS. 



eelf-fertilization through the pollen from them falling 

 upon the female organ or stigma, C. We then procure 

 pollen from the flowers of the other Tariety or species, 

 and apply it to the stigma of the first, or White Lily. The 

 stigma, when in the proper condition for fertilization, is 

 coated with a viscid substance to which the pollen grains 

 will adhere quite firmly, consequently there is little 

 danger of their removal while handling the flower. To 

 prevent insects from visiting the flowers, and interfering 

 with our operations, the flowers should be enclosed in bags 

 made of muslin, mosquito netting, or some similar material 

 soon after opening, and kept enclosed until fertilization 

 is assured ; then removed to relieve them from further 

 restraint. It is always advisable to repeat the application 

 of pollen, because the first may not "take," owing to the 

 immaturity of the stigma. Pollen, however, is not such 

 a delicate material that its potency is readily destroyed 

 by rough handling, and that produced by some kinds of 

 plants may be preserved in good condition for use several 

 days, or even weeks, if excluded from the air. This fact 

 should be kept in mind, for it often occurs that the plant 

 from which we desire to obtain pollen blooms in ad- 

 vance of the one on which we desire to use it. 



In the application of pollen a small camel's hair pencil 

 is the most convenient implement, but where the anthers 

 are large, as in the Lily, a pair of forceps, or even the 

 fingers, may be used for transferring it from one plant to 

 the stigma of another. 



The pollen grains placed on the stigma burst open and 

 discharge their contents upon it, where they may be said 

 to germinate, sending down long flexible filaments or 

 "pollen tubes" through the loose tissues of the stigma 

 and style to the ovary or true seed-vessels, where the 

 completion of the act of fertilization takes place. The 

 exact nature of this act is not fully known, but the 

 mechanical part of the operation is as stated, as may be 



