62 GENERAL PKINCIPLES. 



This impregnation is sometimes, from certain causes, 

 only partially eifected in the cases of fruit where the ovary, 

 or seed vessel, is composed of several cells, as in the apple, 

 pear, etc., and hence the fruit takes an imperfect, one-sided 

 development from the beginning. 



The difficulty that a])pears to arise in the way of the 

 impregnation of the stigma of one flower by the pollen 

 of another, distantly situated, either on the same plant, as 

 in nionfficious trees, or on different plants, as in the dioe- 

 vious ones, is w^onderfully obviated by the provision that 

 nature has made for its transmission — not only by the at- 

 mosphere, but by insects, that pass from one flower to an- 

 other, feeding on their honeyed secretions ; the pollen 

 adhei-es to the bodies of the insects, and th.ey carry it from 

 one flower to another. 



All natural flowers, of the same species, present the 

 same number of petals in their flowers ; but occasionally 

 the stamens are converted into petals, and thus, what are 

 called double flowers, are produced. Among fruit trees 

 we have double-flowering apples, plums, peaches, and 

 chei'ries. These seldom produce fruit ; when perfectly 

 double, never. Many of our double flowers, roses, pceo- 

 nies, etc., have been obtained by this transformation 

 of the stamens into petals. It is supposed to be caused 

 by an excessively high cultivation given to the plants 

 that produce the seeds fiom which these double varieties 

 spring. 



4. Period of Blossoming. — In treating of fruit-buds, 

 allusion has been made to the causes which, according to 

 observation and exj^eiience, promote fruitfulness. These 

 are chiefly a slow or moderate growth, and a branching 

 or spreading, constrained form, instead of an upright one. 

 Some species of trees bloom at a much earlier age than 

 others. Thus the peach, the apricot, and the cherry, will 

 bloom in nearly one-fourth less time from the bud, all 

 things being ecjual, than the pear. Some species bloons. 



