LETTER V. 



# 47 



One main use of the cellular tissue is to bind together 

 the woody fibres, as well as all the other parts of the 

 plant. Its tendency, accordingly, is of a cohesive 

 nature. The tendency of the woody fibres, on the 

 other hand, at least as they exist in the roots," is 

 to separate from one another, to strike off sideways, 

 and spread themselves horizontally in all directions. 

 And this tendency is exhibited in not a few trees (as 

 we have just seen), even in the fibres composing the 

 trunk. To what cause this tendency is more imme- 

 diately owing, we need not now inquire ; but in as far 

 as it is not actively exerted, in so far do the fibres 

 glide passively down, as in a mould, between the last 

 year's layers of wood and bark, and yield themselves 

 to the agency of the cellular tissue. Thus is their 

 real character as roots overlaid and obscured in the 

 trunk. Break down that mould, however ; take away 

 the cellular tissue, and the fibres will stand out even 

 in the trunk as genuine roots. Do you ask for a 

 proof of this assertion ? You have it in the Elm at 

 North Stoneham in this vicinity, of which I give you 

 a representation on the opposite page. It had been 

 dismembered, many years ago, of one of its chief 

 limbs, which had at the same time, in parting, 

 riven and splintered a large portion of the bole, 

 destroying also the cellular tissue there. Since then 

 the woody fibres have continued year by year to 

 pass down from the living and growing parts above. 



