172 SPECIFIC HEAT. 
Specific Heat. 
Trees, considered as organisms, produce in themselves, or in 
the air, a certain amount of heat, by absorbing and condensing 
atmospheric gases, and they exert an opposite influence by 
absorbing water and exhaling it in the form of vapor; but 
there is still another mode by which their living processes may 
warm the air around them, independently of the thermometrice 
effects of condensation and evaporation. The vital heat of a 
dozen persons raises the temperature of a room. If trees pos- 
sess a specific temperature of their own, an organic power of 
generating heat like that with which the warm-blooded ani- 
mals are gifted, though by a different process, a certain amount 
of weight is to be ascribed to this element in estimating the 
action of the forest upon atmospheric temperature. 
Boussingault remarks: “In many flowers there has been 
observed a very considerable evolution of heat, at the approach 
of fecundation. In certain arwms the temperature rises to 40° 
or 50° Cent. [= 104° or 122° Fahr.] It is very probable that 
this phenomenon is general, and varies only in the intensity 
with which it is manifested.” * 
If we suppose the fecundation of the flowers of forest trees 
to be attended with a tenth only of this calorific power, they 
could not fail to exert an important influence on the warmth 
of the atmospheric strata in contact with them. 
Experiments by Meguscher, in Lombardy, led that observer 
to conclude “ that the wood of a living tree maintains a tem- 
perature of + 12° or 13° Cent. [= 54°, 56° Fahr.] when the 
temperature of the air stands at 3°, 7°, and 8° [= 87°, 46°, 
47° F.] above zero, and that the internal warmth of the tree 
does not rise and fall in proportion to that of the atmosphere. 
So long as the latter is below 18° [= 67° Fahr.], that of the 
tree is always the highest ; but if the temperature of the air 
rises to 18°, that of the vegetable growth is the lowest. Since, 
* Leonomic Rurdle,i., p. 22. 
