518 EDWARD B. MEIGS 



gain soon comes to an end and is followed by a fairly rapid loss 

 in weight (fig. 7 and Experiments 34, 35 and 36) . The tissue may 

 remain somewhat irritable for twenty-four hours in the NaCl 

 solution. 



Other experiments have been tried in which pieces of striated 

 and smooth muscle were immersed in 0.9 per cent KCl solution, 

 1.3 per cent K2HPO4 solution, and 1 per cent NaC2H302 solution, 

 all of which have very nearly the same osmotic pressure as a 0.7 

 per cert NaCl solution (fig. 8 and Experiments 64, 65, 66, 67, 68, 

 69, 72 and 73). In the KCl solution the smooth muscle first loses 

 weight and then gains from 45 to 55 per cent of its original weight, 

 though it remains irritable through the twenty hours or more of 

 the experiment. In the other solutions it gains slowly and steadily 

 and to about the same extent as it does in Ringer's solution. It 

 maintains its irritability for about twenty-four hours in these solu- 

 tions also. 



In connection with the question of the reactions of muscle to 

 potassium chloride, certain facts must be mentioned, which have 

 been overlooked by Overton, and which show in a striking way 

 how dangerous it is to theorize about the nature of the semi-per- 

 meable membranes of striated muscle. Overton makes the claim 

 that the surfaces of the living striated muscle fibers are imper- 

 m.eable to the salts of the alkalies and of the alkali earths and to 

 their ions.^^ The evidence for this view is that living striated 

 muscle maintains its original weight in isotonic solutions of these 

 salts. Overton knew, however, that striated muscle swells quite 

 rapidly in isotonic solutions of certain salts, notably KCl, and he 

 thought that the tissue was rapidly killed by an isotonic solution 

 of this salt. He draws a distinction between KCl, KBr, KI and 

 KNO3 on the one hand and K2HPO4, K2SO4, K2C4H2O4 (OH),, 

 KC2H5SO4 and KC2H3O2 on the other.^^ He maintains that in 

 isotonic solutions of the former salts the muscle swells and is 

 soon killed, while in isotonic solutions of the latter it does not 

 swell and is only temporarily paralyzed and its irritability may be 

 quickly restored by transferring it to Ringer's solution. In 



'1 Overton; Archiv fiir die gesammte Physiologie, 1904, Bd. 105, p. 281. 

 22 Overton; Loc. cit., p. 199. 



