290 THE AMERICAN NATURALIST [Vol. XLVII 



though varieties of Vitis vinifera have "been noted by 

 Millardet (1901) as giving only Vitis vinifera progeny, 

 when pollinated by Ampelopsis hederacea. Examples of 

 the parthenocarpic fruits, however, are common. The 

 writer, while attempting to cross the tomato with the 

 Jerusalem Cherry {Solatium Pseudo-capsicum) obtained 

 parthenocarpic tomato fruits, but no fruit of any kind 

 developed when the reciprocal cross was made. Parthe- 

 nocarpic Seckel pear fruits were also produced by the 

 application of Yellow Transparent apple pollen. In the 

 crosses between Nicotiana species already mentioned, 

 seed true to the mother parent was produced ; but as in 

 the case of the Vitis vinifera, there is no positive proof 

 of a parthenogenetic development. What stimulatory 

 effect is imparted by the pollen grain must be due either 

 to an irritation caused by the entrance of the pollen tube 

 or to the exudation of a " growth enzyme.'' 



The Effects of Mutilation 

 The floral and axial organs of the plants were muti- 

 lated by emasculation, by the removal of the anthers, by 

 decapitation, by the removal of both the stigmas and 

 anthers, and by burning various portions of young buds, 

 with the object of upsetting the normal functional proc- 

 esses in such a way as to incite the parthenogenetic de- 

 velopment of seed. To simple emasculation and decapi- 

 tation were added several modifications. Emasculated 

 buds were covered with both paper bags and celluloid 

 covers, but no advantages in favor of either covering 

 could be detected. The decapitated buds were covered 

 with the same two coverings, and in addition buds were 

 left uncovered, but no differences in the results of these 

 three methods were noted. Theoretically, the buds pro- 

 vided with the greatest amount of light and air should 

 be favored in their development, but in this particular 

 case, the results did not permit one to draw conclusions, 

 since only negative results were obtained. Since cap- 

 sules of N. tabacum were found to develop from polli- 

 nated flowers as well under the paper bags as under the 



