194 Striated Muscle Confraction [Jan. 



because the inorganic salts enter the living System and leave it in 

 practically the same condition — they do not undergo combustion or 

 any other chemical change by which appreciable quantities of energy 

 are derived from them.^^ For the present they might be regarded 

 hke the water and the hibricating oil in a steam engine — both oil and 

 water are necessary, but neither are sources of energy. But the 

 argument might be made that altho the inorganic salts are not 

 sources of energy, they transform energy Hberated in the metaboHc 

 processes into surface energy. For this reason the Hmiting values 

 for aqueous Solutions of inorganic salts are of interest. In gen- 

 eral, the surface tension of inorganic-salt Solutions is higher than 

 that of water, but the difference is not great, even for concen- 

 trated Solutions.^ ^ The inorganic salts raise the surface tension 

 of water by an amount approximately proportional to their con- 

 centration. The upper limit for the surface tension of an aqueous 

 Salt Solution is very near 85 dynes per cm.^^ Landolt-Börnstein^^ 

 record some values higher than this for concentrated Solutions of 

 sodium hydroxid (99.7 dynes) and potassium carbonate (107 

 dynes). Since such Solutions do not exist in living matter these 

 values will be disregarded. 



Therefore, if two adjacent regions in a living muscle differed in 

 the fact that one was pure water and the other a saturated aqueous 

 Solution of sodium chlorid or of any other salt present in living 

 tissue, the surface tension between them might be as high as 10 

 dynes per cm., which is the difference between the surface tension 

 of water (75 dynes) and of saturated sodium chlorid Solution (85 

 dynes), both measured separately against air at ordinary tem- 

 peratures. 



There are, of course, still other classes of Solutions ; but the three 

 classes discust are sufficient to definitely locate the upper and lower 

 limits of the surface tension in striated muscle. Of course, the 

 actual surface-tension changes are unknown at present 



13 Sherman : Chemistry of Food and Nutrition, p. 260 (New York, 1911). 



1* Heydweiler : Ann. d. Physik., 1910, xxxiii, p. 181. Lewis : Ztschr. f. physikal. 

 ehem., 1910, Ixxiv, p. 619. Freundlich: Kapillarchemie, p. 62 (Leipzig, 1909). 

 Morgan and Bole: Jour. Amer. Chem. Soc, 1913, xxxv, p. 1750. 



IS Forch : Annalen der Physik., 1905, xvii, p. 744-762. 



Iß Landolt-Börnstein : Physikalisch-chemische Tabellen, 4te Aufl., pp. 128, 129 

 (Berlin, 1912). Castell-Evans : Physico-chemical Tables, ii, p. 768 (London, 1911). 



