26 



BUDS ON ROOTS. 



to the construction of buds from which green leafy shoots sprang up above the 

 surface of the ground. 



A forester of the old school, whose attention I drew to the above phenomenon 

 with a view to ascertaining how he would explain it, told me that when the 

 tree was cut down the flow of sap destined for the nourishment of the trunk 

 and its crown of foliage was arrested in the roots underground, and thereupon 

 sought an outlet elsewhere. Lateral roots having become useless, the diverted 

 juices did not form them, but instead sent a great number of delicate shoots 

 above the ground, because this was the only manner of preserving the life of 

 the Aspen. At first sight this may seem to some people a foolish answer, and 

 I have even heard it called absurd. Nevertheless we are obliged, after impartial 

 consideration, to admit that we are not in a position to give any explanation 

 which is not essentially the same. If we conceive the living protoplasts in the 

 formative tissue of the roots as being the "juices" referred to by the forester, 

 there is no longer any difference between his explanation and that given by 

 Science. At the very spots where formerly lateral roots would have been 

 developed, leafy stems are produced. The same protoplasts which now work 

 at the construction of a bud would, if the tree had not been cut down, have 

 fashioned a lateral root. That this alteration in active function was caused by 

 the felling of the tree is certain, although no mechanical explanation of this 

 stimulus can be given. The only possible source of excitation seems to be the 

 checking of the egress of formative material stored in the roots in the direction 

 in which it was formerly accustomed to flow. 



Another special point of interest connected with the history of this Aspen is 

 that for the most part the roots, after giving rise to a series of shoots, died and 

 decayed, whilst the shoots developed into separate and independent trees, each 

 furnished with roots of its own, so that they look as if they had been deliberately 

 planted in the earth in rows. As a matter of fact, however, the Aspen itself pro- 

 duced these saplings from its subterranean portions, and planted them out, thus 

 not only renewing its own youth but multiplyiag. For such multiplication it is 

 evidently necessary that some cell in that part of the root which possesses the 

 power of growth should form the starting-point or rudiment of a new shoot. The 

 cell chosen for the purpose divides into daughter-cells, and these again become sub- 

 divided; but several adjacent cells also participate in the new fabrication, and we 

 can picture to ourselves the process as the action of a group of protoplasts located 

 within the Hmits of the living and formative tissue of the root, which separate 

 themselves off from the rest and form a confederation of mutually helpful associates 

 with the common function of constructing the new shoot. Neither the protoplast 

 in the mother-cell of the young shoot nor the adjacent protoplasts undergo any 

 stimulation by neighbouring cells before beginning their work. No process of 

 pairing takes place. The phenomenon of renewal and multiplication of the Aspen 

 which goes on before our eyes must therefore be classed as a case of asexual repro- 

 duction. The fact that a single root of the Aspen, instead of producing one sapling 



