370 Plant Physiology 



quently prevent the pollination of the forcing cucumber, 

 especially when it is to be used for fancy market purposes. 

 Certain varieties normally show the development of seeds 

 toward the apical end of the fruit only, and this part is 

 then more or less abnormal in size, so that the general form 

 of the plant is injured. It would appear that in the case 

 of the eggplant a relatively small number of blossoms will, 

 under ordinary circumstances, develop fruit without seeds, 

 and Munson succeeded in obtaining fruits of normal size 

 and form. Many other observations might be cited of the 

 occasional appearance of seedless vegetables, but our chief 

 interest should be directed towards certain observations 

 upon fruits. 



219. Parthenocarpic formation in pomaceous fruits. 

 Waite ascertained that in certain cases self-fertilized 

 pears " are deficient in seeds, usually having only abortive 

 seeds, while the crosses are well supplied with sound 

 seeds." In fact, there were two significant exceptions to 

 the rule requiring pollination and fertilization for fruit 

 development. Upon the Le Conte and Heathcoate 

 varieties a few fruits were set without pollen. Still, in 

 those two instances, there was some doubt as to the com- 

 plete exclusion of pollination. A few isolated instances 

 of the occurrence of pears, apples, and other pomaceous 

 fruits without seed have been recorded, but the possibil- 

 ity of perfect fruit development in certain varieties, or 

 the development of varieties which may not require fertili- 

 zation, has only recently been carefully investigated. 

 Ewert for one has made this matter a subject of experi- 

 mental study, and it would appear that when pollination 

 is prevented, perfect fruits may result in the Cellini and 



