526 STUDIES IN GENERAL PHYSIOLOGY 



I now made a series of experiments with a glycerin solu- 

 tion the osmotic pressure of which was 4.91 atmospheres; 

 which was, therefore, isosmotic with a 0.7 per cent. NaCl 

 solution. I added to 100 c.c. of this solution one-tenth 

 normal LiOH in different quantities from 1 to 4 c.c. In no 

 case did I obtain rhythmical contractions. Similar experi- 

 ments with sugar solutions having an osmotic pressure of 

 4.91 atmospheres yielded the same results. These experi- 

 ments with sugar solutions are, of course, less conclusive, 

 since a portion of the hydroxyl ions are in this case rendered 

 inactive. The addition of 5 c.c. of a one- tenth normal 

 LiOH to 100 c.c. dextrose or cane sugar caused no contrac- 

 tions. Upon the addition of 10 c.c., however, of a one-tenth 

 normal LiOH solution a few weak contractions appeared 

 during the first minute. Beside the experiments with the 

 glycerin solutions the experiments with distilled water 

 adduce proof. In no case did hydroxyl ions in distilled 

 water bring about rhythmical contractions. One might 

 think perhaps that distilled water reduces the irritability so 

 rapidly that contractions are no longer possible. 1 That is, 

 however, not the case. In one case in distilled water the 

 muscle was still irritable after an hour to an induction cur- 

 rent from the induction coil used in all these experiments 

 when the distance of the coils was 310mm., while the normal 

 irritability lay at about 390 mm. Rhythmical contractions 

 occur in solutions of sodium salts at a still lower irritability. 

 The addition of 10 c.c. one-tenth normal LiOH to 100 c.c. 

 of distilled water gave no rhythmical contractions. Even 

 in a one-fortieth normal or one-tenth normal LiOH solu- 

 tion no rhythmical contractions occur. Very weak, one- 

 thousandth to one-hundredth normal LiOH or NaOH solu- 



1 It was found in these experiments that a dextrose solution isosmotic with a 

 0.7 per cent. NaCl solution reduced the irritability of the muscle more rapidly than 

 the NaCl solution; sugar, therefore, is no indifferent substance. That NaCl is not 

 has been proved by Locke. 



