22 



FOEMATION OF ROOTS BY THE STEM. 



wood was foimd to have become a mass of decayed vegetable matter, 

 through which a complete net-work of roots passed to the ground, and 

 extended themselves for a considerable distance from the main stem. 

 Some of these roots were about the size of an ordinary walking-stick. 



Fig. III.— Spanish Chestnut which had thrown out roots under the bark ten feet 

 above the ground. 



On tracing them to their source, they were observed to spring from the 

 edge of the healthy portion of the tree, immediately above the part 

 that had been injured and gone to decay ; and as only a few of the 

 larger ones reached the ground, the whole of the nourishment conveyed 

 by the others to the tree, must have been derived from the gradual 

 decomposition of its own sap-wood. A still more remarkable case is 



