PHYSIOLOGY OF SMOOTH AND STRIATED MUSCLE 



523 



These experiments were carried out before I was aware of the 

 fact that the rapidity with which a piece of smooth muscle swells 

 in a sugar solution depends very largely on the size of the piece of 

 muscle and on the amount of the sugar solution with which it 

 com.es in contact. It will be shown later that a certain amount 

 of sodium (in all probability combined with chlorine) diffuses 

 out from smooth muscle immersed in an isotonic sugar solution; 

 and very small amounts of sodium chloride added to an isotonic 

 sugar solution greatly reduce or prevent altogether the swelling 



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Fig. 13 Changes in weight undergone by two pieces of living smooth muscle, 

 of which one (broken line) was immersed in 7.5 per cent cane sugar solution; and 

 the other (unbroken line) in a mixture containing 19 parts of the sugar solution 

 and 1 part Ringer. At the point marked with an arrow the pure sugar solution 

 was changed. See Experiments 60 and 61. 



of a piece of smooth muscle immersed in it. As evidence for this 

 last statement figure 13 and Experiments 60 and 61 may be 

 cited. 



Experiments with distilled water. A comparison has been made 

 of the behavior of striated and smooth muscle in distilled water 

 (figs. 14, 15 and 16). The discussion of these results will be 

 reserved until later. 



Experiments with acidified Ringer's solution. It has been 

 shown by various investigators that smooth muscle may contain 

 sm.all quantities of lactic acid.^e It is now a well recognized fact 

 that lactic acid plays an important part in the physiology of 



2^ See Saiki; Jour. Biol. Chemistry, 1908, vol. 4, p. 485; Meigs, American Jour. 

 Physiol., 1909, vol. 24, pp. 5 and 6. 



