84 



VITAL ACTIONS. 



some portion of the descending sap forces its way 

 laterally below 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 (Jig. 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 case ; but the American, familiar with the 

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

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

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



