296 POMOLOGY 



tree of a self-sterile variety, thus affording insects an op- 

 portunity to effect cross-pollination. 



When poUination is to be practiced artificially, for exper- 

 imental purposes or for securing new varieties, it is usual 

 to protect the essential parts of the flowers in order to assure 

 accuracy. The blossoms which are to be used as the female 

 parent are inclosed prior to the opening of the petals. The 

 blossoms from which the pollen is to be secured are also pro- 

 tected in order to prevent a mixture with foreign pollen, by 

 insects, or other agency. This covering is usually a paper 

 bag, either manila paper or a translucent, paraffined bag be- 

 ing employed. A question has been raised occasionally as to 

 whether an abnormal condition would not be produced in 

 this way and thus reduce the possibilities of success. How- 

 ever, when coverings of cheese-cloth or other material allow- 

 ing a passage of air have been used, no increase in efficiency 

 has been noted. Others have covered the entire areas with 

 a frame of muslin and either hand-pollinated the flowers or, 

 in case the study is one of self-sterility, bees have been in- 

 cluded. Such an equipment has some advantages, but the 

 percentage of set is not greater than by the bag method. 



In manipulating the flowers, it is customary to cover the 

 blossoms just before they are ready to expand and expose 

 the essential parts. If the purpose is cross-fertilization, the 

 stamens (and often petals) are removed at time of bagging, 

 before pollen has been exposed, so that danger of self-pollin- 

 ation is eliminated. It has been demonstrated that the re- 

 moval of the sepals as well as the petals and stamens has 

 no injurious effect in securing a perfect functioning of the 

 pistils, if carefully done. When the work is performed by 

 a novice or very hurriedly, it is doubtful whether this proce- 

 dure is best, since fruits may be deformed by careless ma- 

 nipulation and many stigmas are often badly injured. The 

 pollen from another tree is frequently collected in a glass 



