THJS CBOSSING OF PLANTS 



249 



rubbed on the stigma by means of a tiny brush, 

 the point of a knife -blade or a sliver of wood. 

 The flower is again covered with the bag, which 

 is allowed to remain for several days until all 

 danger of other pollination is past. 



287a. Care must be taken to completely cover the stigmatic sur- 

 face with pollen, if possible. If one is making scientific experi- 

 ments, it is well to cover the flowers which are to furnish the pollen 

 from the time they are in bud, to make sure that no foreign pollen 

 has been deposited on the anthers (and thereby 

 become mixed with the desired pollen) by wind 

 or insects. 



288. When flowers are in dense 

 clusters it is impossible to cover 

 one of them with a bag, and the 

 operator may not care to pollinate 

 the entire lot; and, moreover, only 

 a part of the flowers in most plants 

 may be expected to mature perfect 

 seeds. (See, for example, the 

 apple cluster in Fig. 46.) In such 

 cases, a few of the flowers should 

 be prepared for crossing, and all 

 the remaining buds should be re- 

 moved. In composites, all the flowers but half a 

 dozen or dozen may be removed from the head. 

 The crossing of flowers is generally not difficult 

 if one has patience and deft fingers, but every 



Fig. 235. 

 Bag prepared for use. 



