THE DISEASES OF PLANTS. 289" 



for if you force a plant to labor beyond its strength, either 

 the fruit will not ripen, or its size and flavor will suffer. 



Caroline. But this pruning, with a view to improve 

 the quality of the fruit at the expense of the quantity, is 

 an unnatural state of vegetation, which, I should suppose, 

 would eventually be prejudicial to a tree. 



Mrs. B. I cannot consider it so : the finest trees and 

 the choicest fruit, are those in which art has judiciously 

 assisted and modified the efforts of Nature. We contri- 

 bute to the health and general prosperity of the tree by 

 preventing it from bearing an excess of fruit; and we make 

 amends for the diminution of quantity by the increase of 

 its size and flavor 



CONVERSATION XXVI. 



ON THE DEGENERATION AND THE DISEASES OF PLANTS. 



Mrs. B. We shall preface the history of the diseases 

 of plants by that of the degeneration of their organs, which 

 often undergo a species of metamorphosis, and, instead 

 of being developed in the usual manner, degenerate into 

 monstrosities. 



There are several causes which produce this effect on 

 plants : 1st. The natural soldering, or cohesion, of the 

 parts. You frequently see the leaves of branches, the 

 petals of flowers, and even fruits which unite, forming 

 double leaves, double flowers, and double fruits. 



Such cohesion sometimes regularly occurs. The single 

 petal which forms the corolla of many flowers, such as 

 the convolvulus, is composed of the union of several 

 others ; but as it is not unfolded until after the junction 

 is completed, we are led to consider it as a single petal ; 

 and such flowers are called in botany monopetalous. 



Emily. But where this union regularly occurs, it 

 should, I think, be considered as the natural state of the 

 plant, and not as a monstrosity. Pray, how does it take 

 place ? Is it a species of grafting one petal upon another. 



Mrs. B. No ; it is rather a simple adhesion than a 



1560. How are the finest trees and the choicest fruits produced! 

 1561. What is said of the degeneration of the organs of plants'? 1562. 

 What is the first of the causes which produce these effects on plants 1 



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