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 1 



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. 2 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. </., one to three 

 minutes) into a solution of a sodium salt whose anion is liable 

 to form insoluble calcium compounds (e. (/., NaFl, Na 3 CO 3 , 

 Na 2 HPO 4 , sodium oxalate, sodium citrate, etc.), the muscle 

 will as a rule not show any reaction except perhaps a slight 



1 American Journal of Physiology, Vol. V (1901), p. 362. 



2 It is possible that certain other ions may act as a substitute for the Ca ions for 

 this purpose. 



692 



