262 NOTICES OF AUTHORS. 



the balancing of so large a trunk, and also for fur- 

 nishing a cover to shield it from the elements ; 

 Thirdly, their superior thickness and induration of 

 bark is, in like manner, bestowed for the protection 

 of the sap-vessels that lie immediately under it, and 

 which, without such defence from cold, could not 

 perform their functions ; Fom'thly, their greater 

 number and variety of roots are for the double pur- 

 pose of nourishment and strength ; nourishment to 

 support a mass of such magnitude, and strength to 

 contend with the fury of the blast." 



On the other hand, in the interior of woods, a 

 universal tendency, for the reasons already stated, is 

 observable in trees, to rise to the light, to attain 

 greater altitude, to form far smaller heads, and tal- 

 ler, slenderer, and more elegant stems. Here is 

 found a milder and more genial climate ; in which, 

 by means of the calm generated by shelter, vegeta- 

 tion is not checked by cold, and, at the same time, 

 is undistm'bed by the external impediment of wind ; 

 and nature has no need, as in the case of exposures, 

 to generate provisions necessary to mitigate the ef- 

 fect of evaporation, as has been above observed, or 

 to endue each indi\idual tree with distinct and ap- 

 propriate means of defence against the elements." 



That, as the four protecting properties, al- 



