OF IlEVEKSED PLANTS. 47 



^. 1 i, of engrafting together three trees standing in a 

 row, and then cutting oif the communication between 

 the central one and the earth, so that it became sus- 

 pended in the air, and was nourished merely through 

 its lateral branches. The same experiment was suc- 

 cessfully practised by the late Dr. Hope at Edinburgh 

 upon three Willows, and in the years 1781, 2, and 3, 

 I repeatedly witnessed their health and vigour. It was 

 observed that the central tree was several days later in 

 coming into leaf than its supporters, but I know not 

 that any other difference was to be perceived between 

 them. The tree which wanted the support of the 

 ground was, some years after, blown down, so that 

 we have now no opportunity of examining the course 

 of its vessels, or the mode in which successive layers 

 of wood were deposited in its branches ; but the ex- 

 periment is easily repeated. 



In the weeping variety of the common Ash, now so 

 frequent in gardens, the branches are completely in- 

 verted as to position, yet the returning fluids appear to 

 run exactly in their natural direction, depositing new 

 wood, as they are situated, above the buds or leaves ; 

 and if the end of any branch be cut, all beyond (or 

 beloxv) the next bud dies; so that in this case gravi- 

 tation, to which Mr. Knight attributes considerable 

 power over the returning fluids, Phil. Trans, for 1804, 

 does not counteract the ordinarv course of nature. 



