XXXIV 
ON AN APPARENTLY NEW FORM OF ABNORMAL IRRI- 
TABILITY (CONTACT-IRRITABILITY ?) PRODUCED 
BY SOLUTIONS OF SALTS (PREFERABLY SODIUM 
SALTS) WHOSE ANIONS ARE LIABLE TO FORM 
INSOLUBLE CALCIUM COMPOUNDS! 
I. INTRODUCTION 
A sERIES of papers published from my laboratory has 
furnished the proof that the rhythmical contractions of 
striped muscles, the swimming bell of jelly-fish, the heart 
and the lymph hearts depend upon the presence of Na ions 
in the surrounding solution. Calcium ions have a tendency 
to diminish or inhibit the contractions altogether, although 
a small number of them must exist in the tissues in order to 
preserve contractility.” This point having been settled, I 
next tried whether the sodium ions bring about these effects 
directly or indirectly. I have not finished these researches 
so far as the rhythmical contractions of the muscle are con- 
cerned, but in pursuing this problem I have found a number 
of facts which show that certain salts can bring about effects 
indirectly by giving the muscle or nerve properties which 
they do not possess normally and which to my knowledge 
have not yet been described. If we put a fresh muscle 
(gastrocnemius) of a frog for a short time (e. g., one to three 
minutes) into a solution of a sodium salt whose anion is liable 
to form insoluble calcium compounds (e. g., NaF], Na,CO,, 
Na, HPO,, sodium oxalate, sodium citrate, etc.), the muscle 
will as a rule not show any reaction except perhaps a slight 
1American Journal of Physiology, Vol. V (1901), p. 362. 
2Tt is possible that certain other ions may act as a substitute for the Ca ions for 
this purpose. 
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