APPENDIX. 2(>.") 



Most of the changes in fruit which are attributed to the influence of cross- 

 pollination are due to variation. Every bud on a tree is dift'erent in some 

 way from every other bud on that tree, and may develop unusual characters, 

 independent of all the other buds, accordinj^- to the conditions under which 

 it grows. 



The best way to determine whether there is an immediate influence of 

 pollen is by hand crossing. Among the forty-five different crosses which 

 were made in 18!)9 with this particular jjoint in view, not one showed any 

 change which could be positively attributed to the influence of pollen. Even 

 the concentrated sweetness of Seckel made no impression on the poor quality 

 of Kieffer; nor were there any constant differences in color, shape, or 

 season of ripening in any of the other crosses. Nearly everybody who has 

 crossed varieties of orchard fruits has had a similar experience. 



Most of the evidence supporting the theory that there is an immediate 

 influence of pollen in the crosses of fruits comes from observation; most of 

 the evidence against it comes from expeinment. The observer, however 

 careful, is likely to Jump at conclusions ; the experimenter tries to give due 

 weight to every influence which might bear on the problem. Since many 

 observers and a few experimenters have found what seems to be an imme- 

 diate influence of pollen on fruit, we cannot doubt but that this influence is 

 sometimes exerted. But it is certainly much less frequent than is commonly 

 supposed. 



THE DISTRIBUTION OF THE POLLENIZERS. 



Having selected a pollenizer with reference to simultaneous blooming 

 and mutual affinity, the fruitgrower now wishes to know how many trees 

 will be necessary to pollinate the self-sterile variety. There are three 

 things to be considered here: The ability of the pollenizer to produce 

 pollen, its market value, and the class of fruit to which the self-steril^ 

 variety belongs. 



Varieties differ in the amount of pollen which they produce, and the 

 pollen production of the same variety is also greatly modified by differences 

 in locality and season. Other things being equal, the variety which produces 

 pollen freely could be used more sparingly in a block of self-sterile trees 

 than one of scanty pollen production. Little comparative observation has 

 been made on this point as yet; but, as a matter of fact, most of our common 

 varieties produce an abundance of pollen. 



The number of trees of the pollenizer would also depend largely on 

 whether it has value in itself. If we are planting LeConte to pollinate 

 Kieffer, we would naturally try to get along with the least possible number 

 which will do the work ; but if Bartletts are to be used for the same pur- 

 pose, we can afford to increase the proportion. Some growers plant every 

 tenth row to the pollenizer, but the proportion should usually be greater. 

 This might be enough if the weather during the blossoming season is very 

 favorable for cross-pollination by wind and insects ; but if it is showery, the 

 pollenizers should be more abundant, in order that cross-pollination may be 

 more general during the bright weather between showers. If using Garber 



