246 PRINCIPLES OF BOTANY, ETC. 
But this heat in vegetables is not of such a nature 
as to enable us to judge of its degree by our senses 
alone. We know that every animal has a certain 
degree of heat. We find a frog or lizard cold, 
‘notwithstanding nature has given them a peculiar 
degree of heat. ‘The temperature of plants is such 
as to enable them to resist both heat and cold. If 
in a hot summer day we touch some ground which 
is much exposed to the rays of the sun, and imme- 
diately after put our hand on green grass exposed 
to sun-shine, we will find the ground much hotter 
than the grass. Fruits, though much in the sun, 
will be cool, whereas a glass full of water will be 
quite warm in a far shorter time. 
Sonnerat detected in the island of Lucon a rivulet, 
the water of which was so hot, that a thermometer 
immersed into it, rose to 174° Fahrenh. Swal- 
lows when flying seven feet high across it, dropped 
down motionless. Notwithstanding this heat he found 
on its banks two species of Aspalathus and the Vitex 
agnus castus, which with their roots swept the water, 
In the island of Tanna, Mr Forster found the ground 
near a volcano as hot as 210° Fahrenh. and at the 
same time covered with flowers. 
This then proves clearly, that plants, like ant- 
mals, have their peculiar temperature, according to 
their native countries, which they cannot exceed 
without injury. ‘he experiments of Dr J. Hunter 
and Schoepf shew us the same thing. The first put 
a Scotch fir, three years old, in a freezing mixture 
of between 15° and 17° Farenh, The youngest 
shoot was frozen; the fir was again planted, the 
young 
