45 
Heat by Wounded Plants . 
while the more rapid circulation is not general through the 
whole of an injured plant, it is propagated with a speed and 
to a distance which is not commensurate with the apparently 
local character of the heat-reaction, so that it would appear 
that the former perhaps precedes the latter. 
That plants should, like animals, respond to the stimulus of 
an injury by an attempt to rally from it is not surprising ; 
but that this rallying should be accompanied by somewhat the 
same symptoms is a matter of no little interest. It is true 
that the reaction is, absolutely, not so marked with a plant as 
with the higher animal ; but when one considers that in the 
former case the cells and tissues are not so interdependent as 
in the latter, and that the whole scale of vitality is keyed to 
a lower pitch, this cannot be wondered at. 
It should be remembered, however, that compared with the 
ordinary temperature of plants over the surrounding medium, 
the rise of temperature after injury is as great, if not greater, 
than in animals. Large or small the reaction is, however, 
sufficiently well marked to justify institution of a comparison 
between the rise in temperature following the injury of plants 
and the fever following the wounding of animals, both being 
due to the exerting of the vital forces of the organism to 
recover from the shock. 
The main results of these experimeiits, as far as is to be 
judged from the objects experimented with, may be stated, in 
brief, as follows : — 
1. That a certain rise in temperature of the adjacent tissue 
follows on the wounding of plants. 
2. That this ‘ fever-reaction’ runs a definite course, attaining 
its maximum some twenty-four hours after injury, so that 
a curve plotted from it corresponds in the main to that of the 
respiration-intensity under similar conditions (Woodcut 2). 
3. That the maximum in all the plants investigated was 
between two and three times the ordinary plus temperature 
of the plant. 
4. That in potatoes (i. e. massive tissues) the effect is local, 
but that in onion-bulbs (i. e. leaves) a much greater extent of 
tissue is sympathetically affected. 
