6 5 5 



Microscopical Essays. 



rind of the birch into fix difiintl coats, and that he had no dcmbt 

 but what the divifion might have been carried much further. 

 Dr. Hill fays, that unlefs fome of thefe coats are obtained in a 

 ftate of feparation from the reft, the .true conftruction of the rind 

 cannot be difcovered, for the connection and form of the parts is 

 loft by the confufion in which they appear while they lie one 

 upon another. 



The following experiments may throw a little light upon this 

 obfcure fubjecl'* All the rind was taken from the trunk of a 

 cherry tree, and the tree thus ikinned, expofed to the air, a part 

 of the bark which was next to the rind dried up and exfoliated ; 

 the part next to this did the fame ; after two or three exfoliations, 

 a farinaceous fubftance covered the fuperficies of the trunk, foon 

 after which a new rind appeared. Some pieces of rind were 

 taken from a few young branches, and the wounds were covered 

 with a cloth that had been foaked in wax and turpentine ; on thefe 

 the rind appeared in a very little time, without any apparent ex- 

 foliation. From fome other branches, not only the rind, but a 

 part of the bark, was alfo taken away, and the wounds covered as 

 before ; a flight exfoliation was obferved here, which was foon 

 followed with a new rind. The bark was taken entirely off from 

 a vigorous cherry-tree, while it was in full fap, fo that the wood 

 appeared the whole extent of the trunk. This was protected 

 from the rays of the fun, and from the air. A new bark and 

 rind formed themfelves upon the trunk, but they did not originate 

 from the bark that was left on the branches and the root, but 

 extended from different fpots, which were firfl formed at con- 



fiderable 



* Duhamel Phyfique des Arbres, torn, p. 12. 



