SAP OF TREES DURING WINTER. 119 



great degree of hardness and durability. If subsequent experiments 

 prove that the true sap descends through the alburnum, it will be easy to 

 point out the cause why trees continue to vegetate after all communi- 

 cation between the leaves and roots, through the bark, has been inter- 

 cepted ; and why some portion of alburnous matter is in all trees * 

 generated below incisions through the bark. 



It was my intention this year to have troubled you with some observa- 

 tions on the reproductions of the buds and roots of trees ; but as the 

 subject of the paper which I have now the honour to address to you 

 appeared to be of more importance, I have deferred those observations 

 to a future opportunity; and I shall at present only observe, that I 

 conceive myself to be in possession of facts to prove that both buds and 

 roots originate from the alburnous substance of plants, and not, as is, I 

 believe, generally supposed, from the bark. 



VI. ON THE REPRODUCTION OF BUDS. 



[Read before the ROYAL SOCIETY, May 23, 1805.] 



EVERY tree, in the ordinary course of its growth, generates in each 

 season those buds which expand in the succeeding spring ; and the buds 

 thus generated contain, in many instances, the whole of the leaves which 

 appear in the following summer. But if these buds be destroyed during 

 the winter or early part of the spring, other buds, in many species of 

 trees, are generated, which in every respect perform the office of those 

 which previously existed, except that they never afford fruit or blossoms. 

 This reproduction of buds has not escaped the notice of naturalists ; 

 but it does not appear to have been ascertained by them, from which 

 amongst the various substances of the tree the buds derive their origin. 



Duhamel conceived that reproduced buds sprang from pre-organized 

 germs ; but the existence of such germs has not, in any instance, been 

 proved, and it is well known that the roots and trunk, and branches, of 

 many species of trees will, under proper management, afford buds from 

 every part of their surfaces ; and therefore, if this hypothesis be well 

 founded, many millions of such germs must be annually generated in every 

 large tree ; not one of which in the ordinary course of nature will come 



* I have in a former paper stated that the perpendicular shoots of the vine form an exception. 

 I spoke on the authority of numerous experiments ; but they had been made late in the summer ; 

 and on repeating the same experiments at an earlier period, I found the result in conformity 

 with my experiments on other trees. 



