. 29*2 ON THE DEGENERATION 



true acacia. The tree we cultivate under that name is 

 derived from North America : it obtained the name of 

 acacia from some resemblance between its fruit and that 

 of the Arabian plant, and was distinguished from it by the 

 title of false acacia : but as the American tree multiplied 

 in Europe whilst that of Arabia was known only to hor- 

 ticulturists, the epithet false was dropped, and it now 

 usurps the name which really appertains to the Arabian 

 plant. Its botanical name is Robinia. 



Instead of wholly disappearing, folioles often degenerate 

 into tendrils, for want of sufficient nourishment. The 

 flower-stalk, or peduncle, is also sometimes converted in- 

 to tendrils. This occurs constantly in the vine. The 

 plant at first shoots out abundance of large leaves and clus- 

 ters of grapes, when, after a time, the food proves insuffi- 

 cient to support such a profuse vegetation ; the new leaves, 

 gradually unfolded, are of smaller dimensions, and the 

 clusters of grapes contracted in size. Still nourishment 

 is wanting, and the later shoots, incapable of developing 

 either flower or leaf, are converted into tendrils. Is this 

 an imperfection in the system of vegetation, or is it not 

 rather a beautiful contrivance, to enable the plant, when 

 it has sprouted all the branches it can nourish, to sustain 

 these branches by means of the tendrils in which they 

 terminate, and which cling to the first object capable of 

 affording them support ? 



Emily. These organs, which you call degenerated, 

 appear to me to serve a purpose no less useful than the 

 functions they would have performed had they come to a 

 state of perfection. But do all the various sorts of ten- 

 drils of climbing plants result from the degeneration of 

 other organs ? 



Mrs. B. There is great reason to suppose so. The 

 most common of these degenerations is the transformation 

 of the young shoots of branches into thorns. When a 

 plant shoots more branches than it can nourish, the most 

 weakly almost wholly cease to grow. The scanty susten- 

 ance they receive serves, however, to harden and strength- 

 en them : hence the tender extremity is converted into 

 an indurated sharp point, capable of inflicting wounds, 

 which you must often have experienced. 



1577. And of that of America 1 ? 1578. And of the degeneration of the 

 folioles and flower-stalks! 1579. How is this seen in the vinel 

 1580. What is the most common of these degenerations'? 1581. How 

 is this effected'? 



