AGRICULTURAL EXPERIMENT STATION. 41 



evidence both for and against the proposition is oljtained from 

 these species of economic importance ; but the question is still an 

 open one. 



As yet there are no satisfactory data on wliich to base general 

 conclusions. It would be unwise, at the present time, to assert 

 that the directing influence of pollen does or does not as a rule ex- 

 tend beyond the fertilization of the seed. It seems not improbable 

 that pollen from a vigorous plant may make an imprint of its 

 character on the female organism which shall be different from 

 that of a less vigorous male parent. It is probable, however, that 

 the vigor and inherent vitality of the plant operated upon usually 

 determines whether this be manifested. Some species show ap- 

 parently unmistakable evidences of the influence of foreign pollen — 

 this is notably the case with peas and Indian corn. On the other 

 hand cucurbitaceous and solanaceous plants seem to resist all 

 foreign influence ; while rosaceous plants are in dispute, with the 

 weight of authority tending to show the absence of immediate in- 

 fluence. 



II. On the Development of the Ovary without Fecunda- 

 tion OF the Ovules. 



A common, though not an universal law of reproduction by seed 

 requires fertilization of the ovules as a condition necessary to the 

 development of fruit. It is a matter of common observation that, 

 as a rule, when pollination fails to result in fertilization, or when 

 pollen is withheld, not only the pistil withers, but the entire flower 

 decays and falls. (Pollination is used in the sense of coition in 

 the animal kingdom, and does not necessarily result in impregna- 

 tion). Instances are not infrequent, however, which point to a 

 responsive action on the part of the pistil or other portions of the 

 flower receiving pollen, while from an insufficient quantity of pol- 

 len, lack of affinity on the part of the species crossed, or some 

 other cause which remains to be determined, fertilization does not 

 occur. Examples of this are specially common in all of our culti- 

 vated fruits and vegetables. 



About the close of the seventeenth century (1691), Camerarius 

 had observed that a female mulberr}' tree once bore fruit though 

 no male tree was in its vicinity. The fruits, however, contained 

 only abortive seeds. Plants of Mercurialis annua being then 



