44 Richards . — The Evolution of 
forth an appreciable amount of the produced heat must be 
lost. It is, however, evident from the experiments in which 
the action of the air was prevented by the application of clay, 
that the phenomena, as regards both respiration 2 and tempe- 
rature (Expt. 1 2 a), are dependent on a supply of oxygen, since in 
these cases a marked diminution of the reaction was noticeable. 
Of interest in this connexion are the results of Eriksson 1 , 
who has shown that the amount of heat produced during 
intra-molecular respiration is but a fraction — a tenth or there- 
abouts — of that which is formed when the same plants are 
respiring under normal conditions. It is not to be wondered 
at then that after injury, when the respiration and hence also 
the vital activities of plants are greatly stimulated, a rise of 
temperature should also be found. 
But it is not a simple question of how much heat should be 
produced by the formation of a given amount of C0 2 , since it 
is living and not dead material which concerns us. There 
are, no doubt, many other changes which take place ; the very 
fact which has already been shown 2 that apparently more 0 2 
is absorbed than is required for the amount of C0 2 produced 
shows that oxidizing reactions may take place which, although 
they do not influence the amount of C0 2 respired, might 
possibly give rise to temperature-changes. Yet in addition to 
these there are no doubt other phenomena attending injury 
which are not to be measured directly by their chemical 
effect. For instance, the acceleration of protoplasmic currents 
which Hauptfleisch 3 has described, affords direct evidence of 
a disturbance of the normal condition of the cell-contents. 
It would be interesting to know from the point of view of 
time how these phenomena are related to those which may 
be determined in a physical or chemical manner : whether 
the accelerated protoplasmic movements precede — which 
perhaps is not impossible — or follow the other phenomena. 
From the observations of Hauptfleisch it would seem that, 
1 Uber Warmebildung nnd intramoleculare Athmung der Pflanzen, Untersuch. 
Bot. Inst, zu Tubingen, Band I, p. 105 et seq. 
2 See previous paper, 1 . c. Table on p. 548. 3 Prings. Jahrb., 1 . c. 
