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1)V die external heat and cold. The cold in their bodies 
is carried to fuch a degree, as in great meafure to put a 
Hop, while it lafls, to the vital fuiuftions. In warmer 
climates no fuch efFecd is produced. In this refpe6t they 
relerable vegetables. 
From the foregoing experiments it appears; firft,that 
plants when in a Hate of actual vegetation, or even in 
fuch a Hate as to be capable of vegetating under certain 
circumftances, mufl be deprived of their principle of ve- 
getation before they can be frozen. Secondly, Vegeta- 
bles have a power within themfelves of producing or ge- 
nerating heat; but not always in proixirtion to the dimi- 
nution of heat by application of cold, fo as to retain at all 
times an uniform degree of heat : for the internal tempe- 
rature of vegetables is fufceptible of variations to a much 
greater extent indeed than that of the more imperfe6t ani- 
mals; but Hill within certain limits. Beyond thefe limits 
the principle of vegetable, as of animal life, reiift s any fur- 
ther change. Thirdly, the heat of vegetables varies, ac- 
cording to the temperature of the medium in which they 
are, which we difeover by varying that temperature, 
and obferving the heat of the vegetable. Fourthly, the 
expence of the vegetating powers in this cafe is propor- 
tioned to the ncceffity, and the whole vegetable powers 
may be exhauHed in this way. Fifthly, this power is 
mod: probably in proportion to theperfeffionof the plant,- 
' the natural heat proper to each fpecies, and the age of each 
individual. It may alfo perhaps de|rend, in fome. degree^ 
on other circumftances not hitherto obferved; for in ex- 
periment 
