4 Descendenz und Hybriden.. 



donne une inflorescence avec trois fleurs normales. La fructi- 

 fication s'est faite comme au printemps. 



Ainsi: 1. La similitude des habitudes du sujet et du greffon 

 n'est pas necessaire ä la reussite de la greffe. 2. On peut 

 rajeunir le Scopolia par greffage sur Tomate. 3. Le greffage 

 peut faire apparaitre dans le Scopolia une seconde floraison 

 annuelle. Bonnier. 



Hartley, Chas. P., Injurious effects of premature poi- 

 Iination. (U. S. Dept. Agric, Bureau of Plant Industry 

 Bulletin. XXII. 1902. p. 1—48.) 



It is generally thought that if pollen is placed upon the 

 stigma before it is receptive, the pollen will germinate later 

 when the stigma is mature, and fertilize the flower. Experi- 

 ments with blossoms of tobacco, Datura latula, cotton, orange, 

 and tomato show that premature pollination is destructive to 

 some flowers. Premature pollination of tobacco blossoms not 

 only results in a failure to set seeds, but the growth of the 

 pollen-tubes into the ovary before the ovules are mature enough 

 to be fertilized, results in an injury which causes the flower to 

 immediately fall. Tobacco flowers pollinated two to three days 

 before the stigmas were receptive feil without setting fruit, while 

 those pollinated one day before becoming receptive gave fair 

 percentages of fruit. Premature pollination of only a portion 

 of the stigma does not cause as great fatality to the flowers as 

 when the stigma is well covered with pollen. Microscopic 

 examination showed that the pollen-tubes in prematurely polli- 

 nated flowers had entered the ovaries, but none were found 

 that had entered the micropyle of the ovule. 



With Datura latula the results were similar, with the 

 exception that the capsules of the prematurely pollinated flowers 

 did not fall from the plants, but hung on for several weeks, 

 although the ovaries did not grow any after pollination and 

 contained no seeds. 



The experiments with cotton showed that it is better to 

 make an extra visit to the emasculated flowers to apply the 

 pollen, rather than to apply it at the time of emasculation. Not 

 only larger percentages of fruit were obtained in this way, but 

 also better fruits. 



With orange blossoms good, well developed seeds will 

 result from flowers pollinated nine days before they would 

 naturally receive pollen. Seedlings from these resulting fruits 

 seem to be as vigorous as any. They also show polyembryonic 

 tendencies as much as others, having from one to four separate 

 plants from a single seed. 



The work with tomato blossoms shows that no injurious 

 effects result from the growth of pollen-tubes in the immature 

 pistils, and also proves the fallacy of the opinion that pollen 

 placed upon young stigmas will remain there and fertilize the 

 flower when the pistil becomes mature. 



