36 THE PLUM IN KANSAS. 



they are so infrequent as to have no perceptible influence on the 

 fruit crops. The several special modifications would need to be much 

 more uniform in their occurrence than I have found them before they 

 could be considered a safe guide to the affinities of varieties for cross- 

 pollination, as suggested by Mr. Heideman. The efficacy of these va- 

 rious forms in securing cross-pollination is yet awaiting demonstration. 



Without reference to adaptations for cross-pollination, it is to be 

 remarked that the species P. americana is exceedingly variable in all 

 its characters, especially in its flower parts, Mr. Heideman mentions 

 a tree in his orchard which uniformly bore flowers with twin ovaries, 

 or even with three united ovaries in a single blossom ; and a case of the 

 same sort has come under my own observation in a scion of a Min- 

 nesota seedling in the orchard of Mr. L. M. Macomber. 



The defectiveness of pistils in many blossoms, however, seems to 

 me to be a more serious matter. It is of much more frequent occur- 

 rence, and appears to represent, in a majority of. cases, a diseased or 

 atrophied condition of the pistil, rather than a healthy modification 

 of form. Professor Goff, who has given this question diligent study, 

 is inclined to attribute many cases of defective pistils to inclemencies 

 of climate, and an examination of the abortive organ itself would give 

 that idea rather than the notion of a definite evolutionary modifica- 

 tion. However, the theory of damage from cold weather is not sup- 

 ported by the notes which we have collected, as will appear later. 



With a view to gaining some light on these questions, a large 

 number of plum blossoms have been examined this spring. While 

 the number of blossoms examined from any single sample was too 

 small to warrant any dogmatic judgment of the variety represented, 

 the total number of blossoms examined (about 2000), and the care- 

 ful manner in which the work was done, under the microscope in 

 the laboratory, will justify us in making some generalizations from 

 the whole. The record of these laboratory examinations will be sub- 

 seqently published in an annual report. 



The term "defective pistils" in this bulletin includes all imper- 

 fections which evidently would make fecundation impossible. In 

 very many cases no trace of style or ovary was foimd. In many 

 other blossoms a small, rudimentary pistil was present, which had 

 plainly ceased to have any vital significance. These several defects 

 seem, for the most part, to be only degrees of the same weakness, 

 whether that weakness be sexual invalidity, evolutionary adaptation, 

 the result of severe weather, or something else. In the aggregate the 

 defective pistils are numerous enough to be taken into serious con- 

 sideration. 



In the laboratory examinations several sami^les showed 100 per 



