INORGANIC RESPONSE 123 
exhibited by muscles, where the first part of the series 
exhibits a staircase increase followed by declining 
responses of fatigue. 
Reversed response due to molecular modification and 
its transformation into normal after continuous stimulation 
(1) in nerve.—Reference has already been made to the fact 
that a nerve which, when fresh, exhibited the normal 
negative response, will often, if kept for some time in 
preservative saline, undergo a molecular modification, 
after which it gives a positive variation. Thus while 
the response given by fresh nerve is normal or negative, 
a stale nerve gives modified, 1.e. reversed or positive, 
response. This peculiar modification does not always 
occur, yet is too frequent to be considered abnormal. 
Again, when such a nerve is subjected to tetanisation 
or continuous stimulation, this modified response tends 
once more to become normal. 
It is found that not only tetanisation, but also CO, 
has the power of converting the modified response into 
normal. Hence it has been suggested that the conver- 
sion under tetanisation of modified response to normal, 
in stale nerve, is due to a hypothetical evolution of CO, 
in the nerve during stimulation.! 
(2) In metals.—I have, however, met with exactly 
parallel phenomena in metals, where, owing to some 
molecular modification, the responses became reversed, 
and where, under continuous stimulation, though here 
1 «Considering that we have no previous evidence of any chemical or 
physical change in tetanised nerve, it seems to me not worth while pausing 
to deal with the criticism that it is not CO,, but “something else” that has 
given the result.’—Waller, Animal Electricity, p. 59. That this pheno- 
menon is nevertheless capable of physical explanation will be shown 
presently. 
