8o3 



of callus, which naturally lacks vessels, though it reaches the thickness of 

 the adjoining parts by a more rapid increase in the lumen of the cells^ 



Opinions differ greatly as to the life period of barked trunks. 



The best example of an unusually long life period in trees which have 

 lost their bark extensively, and have not replaced it, the exposed wood con- 

 sequently falling victim each year to decay, is furnished by Trecul in his 

 description of the linden at Fontainebleau". Yet we have still earlier 

 observations. 



In 1709, Parent reported the following observation to the Academy: 

 An elm in the Tuileries, which at the beginning of spring, 1708, had lost all 

 its bark nevertheless developed its leaves, even if somewhat less vigorously, 

 and kept them all summer. 



DuhameP expresses himself as follows in this connection: Trees with 

 bark wounds, which remain uncovered, gradually go to pieces (sometimes 

 not until four years later). 



At the sitting of the Academy on May nth, 1852, Richard related a 

 case, similar to the one described by Parent as something very extraordi- 

 nary, since, in the majority of cases, the trees die soon after such injuries. 



Gaudichaud* disputes this latter statement by referring to trees in St. 

 Cloud, in the Luxembourg, and at Fontainebleau, which after such injuries 

 lived a great many years, although the outside of the exposed trunk was 

 partially destroyed. 



At the sitting of the Academy of March 7th, 1853, the same botanist 

 returns to this point and now cites the linden at Fontainebleau. According 

 to Trecul, this tree was planted about 1780 and in 1810 was very irregularly 

 barked by some dump carts. On the north side, the barked place was 32 

 cm. long, and began 57 cm. above the ground, while on the south side it 

 was 4.05 m. long and began immediately at the surface of the soil. The 

 barking extended completely around the tree and yet, despite this, the tree 

 lived for 44 years (it did not die until 1854). The diameter at the place 

 of injury was 20 cm., below it, 18 cm. The surface of the injured trunk, 

 the centre of which was so cut by the carts that the diameters of the 

 remainder were 10 and 5^ cm., was entirely worm-eaten and dry. After 

 the dead wood had been removed, the remaining living central portion was 



1 To characterize Trecul's theory, we will g-ive his explanation of the figure, loc. 

 cit., p. 191: A, A' bois de I'annee precedente, V, vaisseaux de ce bois; R rayons 

 medullaires — B jeune bois fonne au printemps avant la decortication. Tons les 

 elements de ce jeune bois, et la partie la plus externe A' de celui de I'annee prece- 

 dente, ont subi un amincissement dans leur membrane. Les cellules externes des 

 rayons medullaires R ont donne lieu a une multiplication utriculaire, quelquefois 

 abondante en r. La multiplication commence aussi en I, I', dans les elements du 

 tissue lig-neux. En g, cette multiplication s'etend a toute la couche I'annee et meme 

 aux rtbres ligneuses les plus externes A' de I'annee precedente. Les vaisseaux qui 

 existaient primitivement dans la couche de cette annee, comme en B, v, sont 

 disparu en g. 



2 Trecul, M. A., L'influence des cortications annulaires sur la yegStation des 

 arbres dicotyledon6s. Annales di. scienc. nat., IV Serie, Vol. Ill, Botanique 1S55, 

 p. 341. 



3 Physique des arbres. Vol. II, p. 46. 



4 Compt. rend, (from 31st of May, 1852). 



