EXPERIMENTS IN ('ROSS- FERTILIZATION. K>9 



plants. A similar series of experiments may 

 be carried out with such plants as coleus, bal- 

 sam, various lilies, tomato, squash, melon, 

 orange, lime, and cacao. 



4. When it is desired to effect cross- 

 fertili/ation with great accuracy, precautions 

 must be taken to prevent the access to the 

 stigma of pollen from any other flower than the 

 one selected. Thus in the last experiment 

 pollen might also have been naturally brought 

 from another flower in addition to that from 

 the one actually used. Choose the flower to 

 receive the pollen while still in the bud-stage, 

 before the anthers have ripened and any pollen 

 has escaped. Gently open the bud and remove 

 the stamens, either by cutting them out by 

 means of fine-pointed scissors, or by pulling off 

 their heads by means of forceps. Protect the 

 flower, thus prepared, from insect visits by 

 covering it with a muslin or paper bag which 

 may be conveniently fixed over a small branch 

 having upon it several prepared flowers After 

 a few days the stigmas will be mature and 

 ready to receive the pollen. Then, temporarily 

 remove the bags and apply pollen from a select- 

 ed flower to the stigmas. Replace the bags 

 immediately and leave them until the flower 

 fades. When this has occurred remove the 



