114 OF THE ROOT, 



aquatic grass, whose root is naturally fibrous 

 and creeping,) growing with an ovate juicy 

 bulb on the top of a dry wall. This variety 

 has been taken for the true A. bulbosus, 

 t. 1249? which has always bulbs even in 

 its native marshes. We see the wisdom of 

 this provision of Nature in the grasses above 

 mentioned, nor may the cause be totally 

 inexplicable. When a tree happens to grow 

 from seed on a wall, it has been observed, 

 on arriving at a certain size, to stop for a 

 while, and send down a root to the ground. 

 As soon as this root was established in the 

 soil, the tree continued increasing to a large 

 magnitude*. Here the vital powers of the 

 tree not being adequate, from scanty nou- 

 rishment, to the usual annual degree of in- 

 crease in the branches, were accumulated in 

 the root, which therefore was excited to an 

 extraordinary exertion, in its own natural 

 direction, downward. There is no occasion 

 then to suppose, as some have done, that the 

 tree had any information of the store of food 



* A particular fact of this kind concerning an ash 

 was communicated to me by the late Rev. Dr. Walker 

 of Edinburgh. See also Trans* of Linn, Soc. v t 2. 2(58. 



