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 

 (i) in nerve. Eeference 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* i.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 C0 2 

 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 C0 2 

 in the nerve during stimulation. 1 



(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 2 , 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. 



