838 



EXPERIMENT STATION RECORD. 



paper sacks. A table is given, showing for each variety the number of 

 blossoms covered, the number of fruits produced from covered blossoms, 

 and the setting of fruits from unprotected blossoms. The following is 

 a summary of the results: 



Eecord of protected blossoms. 



( ; roups. 



Japanese - . 

 Americana 



Nigra 



Miner 



Wayland . . 

 Wild < roose 

 Chicasaw. . 



To fill 



6, 428 



The author believes that these results indicate the self- sterility of 

 all classes and varieties of native plums and of some Japanese plums. 



Natural adaptations for cross-pollination (pp. 89-91, 126-133). — Of the 

 various modifications of flowers by which self-pollination is rendered 

 more difficult, those found most common in case of plums are defective 

 pistils, long styles, and proterogyny. A table is given showing the 

 frequency of these modifications in case of a large number of varieties 

 of the different groups of plums in various localities during the past 2 

 years. The average percentages of defective pistils in the various 

 groups of plums were as follows: Domestica group, 4.3 per cent; Japa- 

 nese, 11.2; Americana, 21.2; Nigra, 17; Miner, 1.9; Wayland, 10.5; 

 Wild Goose, 19.8; Chicasaw, 10.5; Hybrids, 18.1. The author considers 

 defective pistils to' be dependent upon the physiological character of 

 the plant, variety, or species, on the age and health of the tree, and 

 on the storage of food materials. The effect of the health of the tree on 

 the percentage of defective pistils was well shown with Burbank plum, 

 the pistils of a healthy tree being 2 per cent defective, and of a tree 

 d.\ ing from the effect of brown rot fungus 58 per cent defective. As to 

 the storage of food materials the author says: " Repeated observations 

 have shown that buds so situated upon a branch as to command a 

 relatively large storage of food give, as a rule, large blossoms, large 

 ovaries, and perfect pistils; while other buds less favorably situated on 

 the same twigs develop sickly looking blossoms with pistils weak or 

 wanting. Any condition of an entire tree which prevents the normal 

 storage of food materials in buds and branches is likely to show iu 

 defective pistils at the next blossoming season." A tree of Wolf Seed- 

 ling No. 4. which bore much too large a crop in 1896, had not a perfect 

 blossom in 1S97. 



Pollination affinities of varieties and species (pp. 91, 92). — A number of 

 crossing experiments were made to determine what varieties are best 

 adapted to pollinate certain other varieties, but the results are con- 

 sidered by the author to be too meager and contradictory to justify 

 conclusions. 



