GENERAL PHYSICAL CONSTITUTION OF LIVING MATTER 43 



an increase in weight, as a rule, it does not exceed 7 per cent of the 

 initial weight of the muscle. In the corresponding equimolecular 

 solutions of potassium salts, the muscle increases its weight in the 

 same time 40 per cent or more, while in an equimolecular solution 

 of CaClj, it may lose water, sometimes as much as 20 per cent.* In aU 

 these solutions the weight of the muscle changed but immaterially 

 during the first hour. These facts become intelhgible on the assump- 

 tion that the salts diffuse into the muscle, although with less rapidity 

 than the water. As far as the specific action of K, Na, and Ca salts 

 upon the absorption of water by the muscle is concerned, it is some- 

 what analogous to the behavior of various soaps. Potassium soaps are 

 extremely hygroscopic, and absorb water in such quantities as to make 

 them liquid, while calcium soaps absorb but little water; and sodium 

 soaps occupy a position between these two. Soaps contain water in 

 a form in which it can be squeezed out by a slight pressure. The same 

 is also true for some, perhaps most of the water absorbed by muscles, 

 and this holds also, according to Van Bemmelen and Hardy, for the 

 water which is contained in irreversible gels, such as coagulated white 

 of egg or a gel of silicic acid. Such gels evidently contain the water 

 in capillary spaces. Evidently the Na-, K-, Ca-ions ultimately bring 

 about a coagulation in the muscles ; but the structure and size or other 

 physical properties of the interstices in the coagulated material change 

 with the nature of the metal which brings about the coagulation. This 

 is further corroborated by putting the muscle into solutions of a salt, 

 e.g. NaCl, of various concentrations. During the first hour or so the 

 volume of the muscle changes, as one would expect if the muscle were 

 permeable for water, but impermeable or little permeable for salts; 

 but after a longer period a paradoxical result is obtained. In solutions 

 of higher osmotic pressure than the muscle, the latter increases in 

 volume and weight, and within certain limits, the more so the higher 

 the concentration of the solution, as the following table shows : — 



_ »T r^ r. Increase in Weight of Muscle in Twenty-four 



CONCENTKATION OF THE NaCl SOLUTION HoUES IN PeB CenT OF ITS ORIGINAL WEIGHT 



1.05% -H 0.7% 



1.4% + 6.7% 



1-75% +'3%„, 



2.1% +177% 



2.45% + '9% 



2.8% +23-8% 



This experiment might at first suggest that the osmotic pressure is not 

 the force active in this case ; but this is not true. The osmotic pressure 



* Loeb, PJliiger's Archiv, Vol. 75, p. 303, 1899. (A dead muscle absorbs no water in 

 a physiological salt solution, thus showing that the above-mentioned effects of K or Ca can- 

 not be attributed merely to the death of the muscle.) 



