84 



VITAL ACTIONS. 



some portion of the descending sap forces its way 

 laterally belo-w the wound, out of the bark into the 

 alburnum, using the latter as a means of communi- 

 cating with the bark below the ring. 



Some curious experiments upon this subject were 

 contrived by Mr. N. Niven {Gardener's Magazine, vol. 

 xiv.) In one case, he di- 5 



vested the stem of a tree 

 of a deep ring of bark, and 

 of the first twelve layers of 

 wood below it {fig. 5.) ; ne- 

 vertheless the tree continu- 

 ed to live and be healthy. 

 From the exposed surface 

 of the wood no sap made 

 its appearance, except from 

 a cut which had been in- 

 advertently made with the 

 saw on one side, to the 

 depth of, perhaps, five or 

 six layers of Wood beyond 

 the twelve actually remov- 

 ed. From that cut a flow 

 of sap took place, and continued to run during the 

 whole of the season in which the operation was per- 

 formed. In this case, the sap must have ascended 

 exclusively by the alburnum.* 



* [This is a possible ease ; but the American, familiar with th? 

 practice of girdling trees, (which is nothing more than ringing with 

 the hatchet,) so common in the new settlements, well knows that it 

 destroys vitality as certainly as cutting down the tree at once. It 



