on Vegetable Physiology. 



163 



Fig. 21. shows partof a tree, 

 deprived of the whole of the 

 cortical layers, with every ves- 

 tige of the pulp, or cambium, 

 attached to the alburnum. 



This tree continued, for the 

 first year, as healthy and vi- 

 gorous as any of its undis- 

 turbed neighbours ; but, in 

 the second year (Aug., 1837), 

 there were evident signs of less 

 energy and vigour in the tree ; 

 and there is no formation of 

 new bark or wood over any 

 part of the surface of the ring. 

 It has all over appeared dry 

 and inactive. Two develope- 

 ments, however, have been 

 produced, of a very curious 

 and interesting description ; 

 one of which I have not seen 

 noticed by any author : they 

 appear on the tree as shown in fig. 21,, in the shape of roots 

 and branches ; but, as I humbly conceive it would interrupt the 

 description of the rest of the figures too much, to make any 

 lengthened observations respecting them here, besides their not 

 being exactly in connexion with the primary object of inves- 

 tigation, with which I set out, I shall leave the consideration of 

 them till the conclusion, when I shall present the tj'ue speci- 

 mens to speak for themselves ; and then make some observa- 

 tions on these developements. \ujig. 21., a shows the ascending 

 principle producing buds, leaves, and shoots ; and d the 

 descending principle forming wood and roots. 



Fig. 22. represents part of the stem of a tree, deprived in 

 the same way of the bark, liber, and cambium, with two 

 layers of the albiirnous wood. This tree was rather in an 

 unhealthy state when the operation was performed : it con- 

 tinued to live throughout the last year ; shed its leaves rather 

 early ; and this year it developed its leaves, but has since 

 withered away and died. I have every reason to conclude 

 that the operation of ringing accelerated its death. There was 

 no appearance of any flow of sap, either above or below, from the 

 two exposed edges of the layers o^ alburnum ; but there was a small 

 developement of the ascending and descending principles, between 

 the bark and alburiium on the tvpper and lower edges of the ring. 



Fig. 23. represents a tree divested not only of its bak, 



M 2 



