202 Prof. J. Le Conte on the Freezing of Vegetables. 
and unyielding. As it is manifest, that this condition does not 
obtain in any tree, I am disposed to think that this opinion is 
erroneous, and that the effect here referred to, is not the result of 
the phenomenon, young and smail trees would certainly be more 
hable to be cleft; both on account of the greater accessibility 
the contrary, if the effect. is produced by the contraction of the 
exterior layers of wood, we should naturally expect the rifting to 
take place in old trees, where the heart wood is indurated an 
course unyielding, 
he same effect is produced by extreme cold on d 
enon of unequal contraction. pre: | aller 
; precisely analogous to the sm 
fissures produced by rapid desiccation ? : 
3. All travellers in high northern latitudes, testify that the 
bie ag ave Sometimes rent asunder by the intensity of the 
cold, and that the ground is frequently cleft by the same cause, 
* Vide Phil. Trans, vol. xiv. p. 6 i iii 
Vide Phit Trane, wok airs 66 
Phil. i rans. vol, il p- a 
Boyle’s works, vol, ii, pp. 274 et 276, London, 1744. 
