ABNORMAL IRRITABILITY PRODUCED By Sauts 708 
Ca ions as the effect of the sodium-fluoride and similar 
solutions, I wish to state that I consider it possible that 
solution may have other effects which play a réle in these 
phenomena. 
Iv. THE EFFECTS OF SODIUM FLUORIDE AND CORRESPONDING 
SOLUTIONS UPON THE NERVE 
If we try the experiments described above on curarized 
muscles we get little or no result. This would indicate that 
the contact-reaction is not due to an effect of these solutions 
upon the muscle but upon the nerve elements in the muscle. 
There is a second possibility, namely that curare, although 
it does not abolish the electrical irritability of muscle, may 
yet alter its substance enough to prevent the effects of con- 
tact stimuli, or prevent the formation of the hypothetical 
surface layer. 
It may be said with certainty that sodium-fluoride, sodium- 
citrate, and the corresponding solutions act upon the nerve 
in a way altogether different from that in which they act 
npon muscle. If we put the nerve alone(without the muscle) 
into one of these solutions which contains 1 gram-molecule 
in about ten liters, as a rule nothing will happen during 
the first five minutes. The removal of the nerve from the 
solution will not call forth a contraction of the muscle. After 
about five minutes the muscle will begin to twitch rhythmic- 
ally, and very soon the muscle will shorten steadily until it 
reaches a high degree of tetanic contraction. This twitching 
continues as long as the nerve is in the solution. As soon 
as the nerve is taken out of the solution and exposed to the 
air the muscle relaxes more or less completely, and the 
twitchings become less numerous. As soon as the nerve is 
put back into the sodium-citrate solution the contraction in- 
creases again and the twitchings become more powerful. 
This may be repeated very often. It is obvious that the 
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