268 NOTICES OF AUTHORS. 



frequently perish, is most prevalent in cold damp 

 soils, when the air is dry and the sun powerful, and 

 evidently results from the superior vegetation being 

 in advance of the inferior ; torpor of the roots, not 

 torpor of the sap-vessels of the stem from cold. It 

 is also perfectly evident, that trees with long naked 

 stems will suffer most, as their leaves are raised 

 higher, more in the current of the drying wind ; 

 their root and top farther asunder, therefore less 

 liable to contemporaneous impulse ; the sap-vessels 

 of the stem longer and more attenuated, therefore 

 the streams of fluids from the soil, not only smaller, 

 but also more liable to obstruction, or to flow slowly, 

 from the insufficiency of the vital impulse, or of en- 

 dosmose in the wounded sickly plant to impel to such 

 a height. Our author's assertion, that the rough epi- 

 dermis generally covering the live bark of trees in 

 open situations, is necessary to the health of the tree, 

 in protecting the sap-vessels from cold, is, we think, 

 not quite correct. Some time ago we caused the dead 

 epidermis be hewn down from several trees, in a ra- 

 ther exposed situation. This was done vdth consi- 

 derable nicety, and extending up along the branches. 

 We remember of one case, of very thick indm'ated 

 epidermis, where a carpenter was employed more 

 than a day in laying bare the live bark of one tree. 



