ELECTROLYTES AND MUSCULAR CONTRACTION. 55 



and .03 A 7 respectively, and that of the NaNO 3 was raised from 

 o.i 5 A 7 to .03 5 A 7 , differing by ,oo$N in each successive so- 

 lution. 



Solution 10 was the calculated solution. In solutions 11-15 

 the concentrations of the LiNO s and NaNO 3 were kept at .135^ 

 and OI5A- 7 respectively, while the concentration* of the NH 4 NO 3 

 was decreased from .O2N in 1 1 to .oooA^in I 5 by steps of .005 A 7 . 

 In solutions 1619 the concentrations of the LiNO., and NaNO, 



^ o o 



were kept at .135^ and .oi5A r respectively, while that of the 

 NH 4 NO 3 was raised from .03 lA^in i6to .034.^ in 19 by steps of 

 .001 A r . In solutions 20-23 the concentrations of the LiNO 3 and 

 NH 4 NO 3 were kept at .i35A r and . 03 A r respectively, and the con- 

 centration of the NaNO 3 raised from .oi6A^to .oigNin steps of 

 .ooiA'. Out of all the twenty-three solutions thus tried the 

 only ones which approximated to the Ringer as sustainers of 

 the heart-beat were the calculated solution (10) and solution i 

 (.i35^VLiNO 3 4- -O3A 7 NH 4 NO, 4- .01 5 A^NaNOJ in which //[>(;/ 

 4- ?')] = 629.5 --and these are the two solutions which approxi- 

 mate most closely to Ringer in the value of ?//[?'(// 4- i')] . Thus 

 solution i i (.i35.VLiNO 3 4- .O2A T NH 4 NO 3 + .01 5A r NaNO 3 ) was 

 much less efficacious than the calculated solution. On estimating 

 the value of ?//[T'(;/ + ?/)] for this solution the reason becomes 

 clear, for its value is 6 1 5. i, a value departing comparatively widely 

 from that for Ringer or for solution 10. The other solutions in 

 which the NH 4 NO 3 concentration was still further lowered (11- 

 i 5) were still more deleterious. Raising the concentration of the 

 NaNO s above that in solution i was also deleterious (solutions 

 6-9), and it will be found that in these solutions the value of 

 it [?-(// 4- 7')] rises above 630, as might be expected ; raising the 

 concentration of the NH 4 NO., (solutions 1-5) was still more 

 deleterious. 



In solution 10, to quote one experiment, a heart washed in 

 NaCl and beating initially at a rate of 10 in 15 seconds, continued 

 beating for 65 minutes ; in i, a heart beating initially at the same 

 rate and treated in the same way as the above, and at the same 

 time, beat for from 40-60 minutes ; while a third heart, in 

 Ringer, and beating initially at the same rate as the other two, 

 beat for 90 minutes. 



