PROPAGATION. 213 



thing similar might be observed in other trees. Such 

 a circumstance, however, admits of easy proof, though 

 it has not been sufficiently tried ; because if we graft 

 a pear on a quince, in a series of years the original 

 axis of the quince stock will be covered by the annu- 

 ally or occasionally downward prolongations of the 

 pear ; and if then a cross section of the stem below 

 the graft be made, the wood of the quince will ap- 

 pear in the centre, surrounded by that of the pear, 

 the original bark of the stock remaining on the exte- 

 rior. But that this does take place, is positively 

 denied ; no portion of the substance of the graft is 

 ever seen to descend much below the place where it is 

 united to the stock ; and therefore some other cause 

 must be assigned for the appearance of variegated 

 leaves on the suckers. 



A curious experiment, long ago performed by Du 

 Hamel and others, has lately been made, by extract- 

 ing a hoop of bark from the sycamore- leaved maple, 

 and substituting another of equal size of red maple. 

 A perfect union took place ; and, after some time, the 

 part was examined ; and the new wood formed under 

 the red maple bark was found to be that of itself, and 

 not that of the sycamore, which it would have been 

 had ligneous fibres of the latter descended from its 

 buds above. Observations sur la Structure et la 

 Mode cT Accroissement des tiges dans quelque Families 

 de Plantes Decotyledones. Par M. Adolphe Brong- 

 niart. Acad. de Scien. Paris. 



On this experiment we may remark, that it point- 



