138 SEAT OF VEGETABLE LIFE. 



vitality is constitutionally compound, not simple, as 

 such a thin tissue may be supposed to be. That it 

 is annually divided into three portions is perfectly 

 obvious by ocular demonstration. In early spring 

 it is a thin layer, in the autumn this same layer is 

 divided into alburnum, liber, and the remains of 

 itself. It is, moreover, subdivisible into separate 

 small parts longitudinally, each of which contains 

 the specific essentials of the whole, namely, the 

 formation of bark and wood, and the rudiments of 

 roots and shoots. 



This last assertion is verified by what is often seen 

 on the surface of the alburnum of a decorticated tree. 

 The surface of the alburnum is unequal ; it is varied 

 by little furrows or crevices, and which, when the 

 bark is stripped off, retain, in some instances, small 

 portions of the envelope. These insulated portions, 

 however, soon show their vital property by swelling 

 from their stations, and by spreading themselves 

 over the naked wood, assist materially to close the 

 wound. 



The foregoing observations are intended to support 

 the idea, not only of the identity of the vital envelope 

 as a distinct member of the system, but also its com- 

 pound character as containing the rudiments of both 

 roots and buds ; and, moreover, the source of all 

 accretion, whether as to the magnitude or number of 

 the parts produced. 



That a finite quantity or number can be infinitely 

 divided has always been a mystery, except only to 



