PHYSIOLOGY OF SMOOTH AND STRIATED MUSCLE 



525 



striated muscle, and it is an interesting question what effect small 

 quantities of acid would have on the tendency of the smooth 

 muscle fibers to imbibe fluid. 



A number of experiments have been carried out with the view 

 of answering this question. It is, of course, not practicable to 

 add the lactic acid to the Ringer's solution described on p. 505, 

 for the NaHCOs contained in that solution would react with small 

 quantities of the acid. For this reason the behavior of pieces of 

 smooth muscle in Ringer's solution has been compared, on the 

 one hand, with the behavior of pieces of muscle in a Ringer solu- 

 tion from which the NaHCOg has been omitted, and, on the other, 



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Fig. 17 Changes in weight undergone by two strips of living smooth muscle, 

 of which one (broken line) was immersed in Ringer's solution; and the other 

 (unbroken line), in a Ringer solution in which 0.01 per cent of lactic acid had 

 been substituted for the NaHCOs. See Experiments 27 and 28. 



with the behavior of pieces of muscle in a Ringer solution in which 

 a small quantity of lactic acid has been substituted for the 

 NaHCOs. The results have shown that similar pieces of muscle 

 gain weight to about the same extent in Ringer's solution and in 

 Ringer without NaHCOs; but that the tendency to gain weight 

 is almost absent in a Ringer solution in which 0.01 per cent of 

 lactic acid is substituted for the NaHCOs, and is soon succeeded 

 by a tendency to lose weight (fig. 17 and Experiments 10, 11, 16, 

 27, 28, 36, 37 and 53). 



Pieces of smooth muscle tend to take up fluid from a Ringer 

 solution in which larger quantities of lactic acid have been sub- 

 stituted for the NaHCOs (Experiments 23 and 24). 



