316 REPORTS ON THE STATE OF SCIENCE. 
experiment the question formerly put as to whether muscle and nerve 
are excitable by thermic stimuli. This retrial was all the more necessary 
in that, although the original publications of fifty and thirty years ago by 
Valentin, Eckhard, Pickford, and Grutzner give answers that are in 
substance in the negative, most recent text-books of physiology include 
‘thermic stimuli’ in the list given of the various kinds of stimuli by 
which nerve and muscle can be excited. So that anyone coming fresh to 
the subject would be justified in assuming as a fixed datum of accepted 
knowledge that muscle and nerve can be excited by thermic shocks, 
whereas, as a matter of fact, the results of experiments, when first wit- 
nessed fifty years ago, were more than doubtful, and there is no subse- 
quent sign in the literature of the subject to indicate that the experiments 
have ever been tried again; far less has any demonstration been given 
of either an affirmative or a negative answer to the question. 
Paper No. 1! reports the experiments and results from which we draw 
the conclusion that the stimulation of nerve by the brief localised applica- 
tion of heat cannot be demonstrated by any regular effects in the muscle 
or in the galvanometer, the effects, if any, being irregular (and irrever- 
sible) and attributable to desiccation. Therefore the answer to our ques- 
tion, ‘ Do thermic shocks act as nerve stimuli?’ is a clear negative. It 
need hardly be added that the answer applies solely to nerve fibres, and 
not to nerve terminations, and that it does not involve the well-known 
influence of heat upon excitability to ordinary forms of stimulation. 
Paper No. 2? gives an account of experiments made in answer to the 
question, ‘ Do thermic shocks act as muscle stimuli?’ It is more 
difficult to answer by a decided ‘ Yes’ or ‘No’ to this question, 
because, on the one hand, muscle gives a contraction at each thermic 
shock that is to all appearance a ‘ sign of life,’ in which case the answer 
is ‘ Yes,’ and, on the other hand, altogether similar ‘ contractions ’ 
can be obtained on nerve that are assuredly not a ‘ sign of life,’ in which 
case the answer is ‘No.’ The balance of probability is, therefore, that 
the answer is, as before, in the negative. 
Paper No. 3% contains conclusions that we regard as being of very 
considerable general importance towards a comprehension of the chemical 
changes underlying excitatory effects in animal and vegetable tissues, 
and offers evidence of an opposition between the electrical effects of 
excitation and those of a brief application of heat. 
As regards animal tissues we investigated isolated muscle, isolated 
nerve, and isolated skin; as regards vegetable tissues we used pea and 
bean seedlings and the young fronds of maidenhair ferns. We com- 
menced by observations on the sartorius muscle of the frog, repeating, 
under improved conditions of experiment, the observations of Worm- 
Miiller and Hermann, whose results we considered to be inconclusive. 
The uniform result of our observations, from which the fallacy caused 
by thermo-electric currents was carefully excluded, was to the effect that 
the brief local application of heat (by means of a current of warm air) 
is to render the warmed spot ‘ anti-zincative’ (galvanometrically 
positive) to any normal unwarmed spot ; on repetition of the application 
1 Do thermic shocks act as nerve-stimuli? Proc. Physiol. Soc., January 23,1909. 
2 Do thermic shocks act as muscle-stimuli? Jbid., February 27, 1909. 
§ The effect of heat upon the electrical state of living tissues. Proc. Physivl. 
Soc., February 27, 1909, and Proc.F.S., vol. 81 B., p. 303, 1909. ‘ 
> 
