ON THE ROOTS AND STUMPS OF SILVER FIR. 



475 



I have seen old stumps of the silver fir which, according to certain 

 marks, had been felled forty- five years before, still full of life. The 

 interior was entirely decayed, but the outer wood and the bark pre- 

 sented signs of life. These observations were made in the spring ; the 

 stump and the roots being full of sap, the bark, separated from the wood 

 by the effusion of the pulp, {cambium,) was easily detached. This 

 bark, and the wood adjacent, had all the appearances which these parts 

 present when in a flourishing state. The existence of the pulp {cam- 

 bium) indicated that the stump was increasing in diameter. This point 

 I was also able to prove, which I did in the following manner. I per- 

 ceived that a kind of enlargement was formed between the bark and 

 the wood of the stump, and that this swelling, consisting of the wood 

 and bark which had been produced since the tree was felled, had again 

 covered a portion of the transversal section of the stump, so that the 

 section of the sap which limited the central system of the tree at the 

 time of its being felled, was in perfect preservation. The traces of the 

 axe on this sap, transversely divided, removed all doubt on this point. 

 I have also seen on all these stumps an increase in the diameter from 

 the production of new pulp, the thickness of which, in the old branches 

 which I examined, was about two-fifths of an inch, so that these stumps, 

 during the space of forty-five years, had acquired a total increase of 

 four-fifths of an inch, or eight lines in diameter. 



The phenomenon which the silver fir presents in such circumstances 

 appears at first sight to invalidate the theory which supposes the sap 

 furnishing the materials of growth to be derived from the leaves or the 

 umbrageous parts of the vegetable. But the extreme scantiness of the 

 increase in the diameter of the stump of the silver fir, on the contrary, 

 confirms this theory ; for the stump which continues to live during so 

 great a number of years increases thus slowly from the want of leaves, 

 which are peculiarly the productive organs of the nutritive pulp. It 

 appears that the roots of this tree possess the faculty of producing a 

 small quantity of crude sap, and of converting it into nutritive pulp, 

 which preserves life in the roots and stump, and contributes to their 

 scanty growth during a great number of years. This faculty is wanting 

 in the Norway spruce and the Scotch fir, {Pinus sylvesfris?) of which 

 the stump and roots die soon after the tree has been felled. Whence 

 arises this difference ? This is a question not easily decided. How- 

 ever this may be, the fact is very remarkable which proves that the 

 roots of trees, and the small portion of the stem which is left when 

 they are felled, do, in certain cases, live a long time and increase, 

 though not surmounted by any foliage. 



