Prof. J. Le Conte on the Freezing of Vegetables. . 91 
show, that the temperature of the interior of small trees, shrubs 
and twigs, is sensibly the same as that of the surrounding atmos- 
phere; and the difference becomes more apparent the larger the 
trunk on which the observation is made, and the nearer it is to 
the ground. It is manifest, therefore, that,—so far as the buds 
and smaller branches are concerned,—the cause under considera- 
tion, can have no practical influence in enabling vegetables to re- 
sist the action of excessive cold: its effect must be infinitesimal. 
Moreover, it will be shown hereafter, that perennial plants, and 
even large forest trees, endure the intense cold of a Siberian win- 
tet, when their roots are imbedded in a soil which is frozen more 
than one-half of the year. 
5. After what has been said above, it is unnecessary to dwell 
on the influence of the bad conducting power of the concentric 
layers of bark, or on the greater facility with which the wood it- 
self transmits heat longitudinally than transversely, as proved by 
the experiments of MM. Aug. de La Rive and Alph. De Can- 
dolle.* These circumstances only prevent the supply of caloric 
which is pumped up by the roots from the warm earth, from be- 
img carried off ; but as we have shown, that no appreciable amount 
of this heat can possibly reach the extreme twigs and buds, it is 
Sufliciently evident, that the low conducting power of the wood 
layers and bark can have no sensible influence in resisting any 
atmospheric changes which might be injurious to these portions 
of plants,t 
_ lis proper to remark, that until quite recently, I participated 
in the opinion so generally prevalent among the most eminent 
Physiologists, that the sap of trees and shrubs which are unin- 
jured by extreme cold, is never frozen. I, therefore, entered upon 
investigation with all my prepossessions in favor of the com- 
Mouly received opinion in relation to this subject. Nevertheless, 
2 glaring inadequacy of all the causes which have been assign- 
ed; to explain the presumed fact, induced me, during the winter 
+ 850-51, to institute a series of observations and experiments, 
With the view of obtaining clearer ideas. ‘The sequel will show, . 
* was very soon driven to the conclusion, that the funda- ° 
mental idea is erroneous, and that plants do become frozen with- 
out the slightest injury to them. nes agen 7 
leas the morning of the 18th of November, 1850, I f ind. the - 
ves 
of the common garden cabbage covered with hoar frost — 
ae surfaces, and so completely frozen as to be quite _— 
st. * : 
ff. N more minute examination, it was found, th 
se le lc ° on fs ‘ 
Amn. de Phys. xl 
considerations seem to show, that those phytologists who are disp : 
at this subject in a teleological point. of view, have mistaken the true office — 
i They can 
* Mém, Soe. de Phys. de Genéve, vol. iv, p. 71; also, 
totarbese 1 to Ww, 
of 
sexing al? which envelop the buds of plants. 
action of cold, 
