WATER ABSORPTION BY MUSCLES AND SOAPS 513 



The analogy between the behavior of soaps and of muscles 

 is of importance for the mechanics of the absorption of 

 liquids. The majority of authors for example, Hofmeister 

 assume that in the absorption of liquids by tissue we 

 deal with imbibition; that is to say, with capillary phe- 

 nomena. In the absorption of water by soaps, however, we 

 deal with phenomena of solution. 1 The forces concerned in 

 the latter are osmotic pressures, and not surface tensions, as 

 in capillary phenomena. 



The antagonism which has been shown by these experi- 

 ments to exist between potassium and calcium compounds is 

 of interest in another direction. Ringer has called attention 

 to the fact that an antagonism exists between calcium and 

 potassium salts in their effect on the heart. The latter are 

 supposed to favor the diastole, the former the systole, of the 

 heart. Howell has adopted the views of Ringer. Possibly 

 the above-described characteristics of the two substances may 

 help to explain the phenomena of contractility. I cannot 

 assent to the view that calcium is the "stimulus" for the 

 cardiac activity. Years ago this might have been errone- 

 ously said about oxygen. The cause of cardiac activity (as 

 that of every automatic activity) is neither calcium nor oxy- 

 gen, but heat, or, more correctly, its intensity factor, tem- 

 perature. Calcium and potassium might be of importance 

 for the changes in the amount of water in various elements, 

 or for their state of matter, and so be of importance for the 

 contraction of the heart. 



II 



I had shown in my earlier publications that when a trace 

 of acid is added to a 0.7 per cent. NaCl. solution, a muscle 

 immersed in it absorbs a large amount of water. 2 I was 



1 This statement will probably have to be modified. Sinee water can be removed 

 from soaps by pressure, it is at least partly held there by imbibition. [1903] 



2 " On the Physiological Effects of Ions," Part II, pp. 450 and 501. 



