APPENDAGES OF THE AXOPHYTE. 41 



body of the tree, after which each limb, being severed from the 

 parent, forms a new tree. 



Separate pieces of young stems containing a bud, and called 

 by gardeners cuttings, will also take root if due care be taken 

 with them. For a tree is not an individual, as is commonly 

 supposed, but a collection of individuals, an elongation of indi- 

 vidual buds, which, in their development into branches, live 

 on their parent stem, into which they send down roots just as 

 that parent stem itself sends its roots into the soil. For this 

 reason the bud of one plant may be transferred to the stem of 

 a similar or nearly related species, to which, if it be carefully 

 fitted, it will soon become rooted and develope into a branch, 

 being sustained by the stem, into which it has been engrafted 

 equally with the natural branches of the tree. 



The observations of Mohl and linger, both eminent physio- 

 logists, have proved that adventitious or aerial roots are all 

 formed in a very similar manner. They show themselves at 

 first under the form of a little conical excrescence or tubercle, 

 the base of which rests on the wood. As they increase, they 

 turn aside the cells of the tuber and cortical parenchyma which 

 they traverse, and finally form a slight prominence under the 

 epidermis. A little later, the epidermis is torn in a direction 

 parallel to the axis or stem, and the root shows itself at the 

 exterior and directs itself towards the soil. 



The roots of plants generally bury themselves in the soil, 

 but some plants are parasites (rfapa beside, altos food), or 

 derive their nutriment from the plants on which they grow 

 and into which they fix their roots, and cannot therefore be 

 cultivated on the ground. Some parasites grow on the roots 

 of trees, as the Epiphegus Virginiana, or beech drops, which is 

 found beneath the shade of beech trees, and on the roots of 



