24 Absorption of Liquids by Animal Tissues 



and on the lymph-heart of frogs, showed that the solutions mentioned above have 



poisonous effects in these latter cases. We are, therefore, supported in the assumption 



that the time effects may be due to certain physiological changes in the muscular 



tissues resulting, possibly, in formation of various products of enzymic activity, which 



products would increase the osmotic pressure inside the muscle and therefore cause h 



later absorption of fluid. 



III. ionic effects 



(a) If a muscle be immersed in a ^m NaCl solution for twenty-four hours it 

 gains but slightly in weight. In a solution of ^m KCl (isosmotic with ^m NaCl) the 

 gain is 40 per cent., while in a solution of ^^m. CaCl the loss is 20 per cent. From 

 the previous sections of this paper the variations in the effects of cations Na, K, NH4, 

 Ca, Mg, Ba, and anions SO4, C2O4, C6H5O7, CO3, CI, and NO3 will be evident. It was 

 shown above that osmotic pressure differences could not account for the divergence 

 noted when isosmotic solutions of various salts were used. Loeb, in his work on 

 absorption by muscle, advanced the following theory to explain the phenomenon noted 

 at the beginning of this section. " Salts or electrolytes in general do not exist as such 

 in the living tissues. In the muscle the various metal ions exist in combination with 

 the proteid, in which combination they may be easily substituted, one for the other. 

 In this substitution certain physical properties of colloid, especially their power of 

 absorption of water and their state of matter, are changed." According to this "ion- 

 proteid" theory, we should expect that, no matter what the outside solution might be, 

 the ions of this solution would enter the muscle and substitute themselves for the ions 

 present in the muscle. It is a well known chemical fact that we have combinations of 

 metal ions with the radicals of the higher fatty acids forming a distinct class of 

 compounds known as soaps. Potassium soaps absorb large amounts of water, in fact 

 they constitute the class of soft-soaps, which have an almost fluid consistency. Sodium 

 soaps absorb only a slight amount of water, while the calcium soaps are very insoluble 

 and absorb none. The effects of ions upon absorption by muscle are to form "ion- 

 proteids," which effects show a " remarkable parallelism with the influence of the 

 same ions upon absorption of water by soaps." The effects of Ba and Mg ions are 

 quite different from those of Ca ions. Chemically speaking, we might expect these 

 former ions to behave like Ca ions, yet, physiologically considered, effects do not 

 always follow chemical characteristics. Our first idea of the cause of this variation 

 was that, inasmuch as MgCl2 is hydrolyzed in solution to MgOHCl and HCl, we might 

 be dealing here with an action of the H ions of the HCl, This is not a very plausible 

 conclusion, as the hydrolysis is so slight that such a marked result could hardly follow. 

 This was further shown to be untenable when the action of BaCl2 was investigated. 

 This salt is not at all hydrolyzed in solution and can therefore have no free H ions in 

 its solution. As the effects of BaCl2 and MgCl2 are almost identical, we must assume 

 that we are dealing with the same cause in each case. We therefore revert to the ion- 

 proteid theory and conclude that Ba- and Mg-proteid compounds show much the same 

 absorptive power as do the K-proteid combinations. That Ba and Mg soaps show this 



126 



