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mechanism properly so as regularly to effect cross-pollination. The wings and keel 

 move together. Short-tongued bees are unable to reach the nectar, but honey 

 bees are responsible for most of the pollination. 



The Plum Blossom. The white flowers and nectar are attractive to insects. 

 The Americana flowers are slightly protogynous, so that when they open they are 

 ready to receive pollen. The Domestica flowers are more protogynous than the 

 Americana flowers, so that they are more likely to be cross-pollinated. Infertility 

 of pollen prevents fertilization even when self-pollination occurs. 



Raspberry and Blackberry Blossoms. These blossoms have white petals 

 and abundance of nectar, but those of the blackberry are more attractive. The 

 stigma is receptive before the stamens mature, so that cross-pollination is facili- 

 tated. In both species, honey bees are the main pollinators. 



Gooseberry and Currant Blossoms. These secrete nectar and are visited 

 by honey and bumble bees. In one of these species the flowers are dioecious; 

 that is, the staminate and pistillate flowers are on different plants. In the rest, 

 the relative positions of stamens and stigmas secure cross-pollination. 



The Strawberry Blossoms. Inasmuch as many of the cultivated varieties 

 of the cultivated strawberry are staminate and pistillate, cross-pollination is 

 absolutely essential to fertilization. " Nectar is secreted by the receptacle at the 

 base of the filaments next to the outer row of pistils." Honey bees and short- 

 tongued bees are the main pollinators. 



4. Direct Evidences. The direct evidences obtained by means of experi- 

 ments and observations show clearly that bees are very important factors in the 

 pollination of orchard fruits and the various species of clovers. 



The Apple. Waite, of Washington, covered many blossoms with gauze 

 netting, and out of 2,586 only three apples set fruit. '' Of these the Baldwin, 

 Spitzenburg, and Fameuse set some fruit." Further experiments showed that 

 even the Baldwin, which is often self-fertile, gave much better results (4 times) 

 when cross-pollinated. The Greening, Talman Sweet, Spitzenburg, and Twenty 

 Ounce gave very poor results from self-pollination. Waite concluded from his 

 experiments that cross-pollinated apples were " larger, more highly colored, and 

 better supphed with seed."— (Year Book, U.S. Dept. Agr. 1898, p. 177.) 



The Pear. Waite's experiments on pollination of the pear show convincingly 

 that pears require cross-pollination. He found the Anjou, Bartlett, Clapp's 

 Favorite, Clairgeau, and others completely self-sterile, while the Flemish Beauty, 

 Seckel, and Angouleme to be more or less self-fertile. The Kieffer and LeConte 

 are self-sterile in the north. 



