264 PHYSIOLOGY OF TREF.S. 



narrow compressed line. Yet, in this slender 

 cylinder of vitality, it may reasonably be inferred, 

 are comprised an infinite number of layers of 

 incipient alburnum as well as of bark. 



In a former part of this work it has been 

 stated, in describing the physical conformation of 

 bulbs, that their radical plates are composed of an 

 endless succession of gems, which are developed 

 in the order of their seniority ; so the vital en- 

 velope of a tree is annually and constantly divisi- 

 ble into layers of bark and wood for ever 



This narrow shell of vitality did contain all 

 the buds and roots that have been, and does con- 

 tain the rudiments of all that ever will be de- 

 veloped ; the gems not floating loosely in the sap, 

 as has been conjectured, but borne on the vital 

 membrane and there remaining inert, or de- 

 veloped when circumstances are favourable. 

 These gems, though imperceptible, from their 

 extreme minuteness, are variously located in the 



Though trees which do not stole are liable to decay 

 after a certain period, yet those that do^ or are capable of 

 being perpetuated by art, may be said to continue for ever. 



