438 



SCIENCE 



[N. S. Vol. XXXVII. No. 951 



NaCl solution, it loses considerably in an 

 m/110 acid 4.9 per cent. NaCl solution.^*' 



The writer also pointed out that the 

 chemical character of the salt was of great 

 influence in this phenomenon. While it 

 required a high concentration of NaCl and 

 of acid to cause a dehydration, the same 

 was accomplished by a much weaker solu- 

 tion of K2SO4. In a neutral isotonic solu- 

 tion of K2SO4 the muscle lost 4 per cent, in 

 eighteen hours, but when 10 c.c. m/10 HCl 

 were added to 100 c.c. isotonic K2SO4 solu- 

 tion the muscle lost 22 per cent, of its 

 weight! The concentration of KjSO^ re- 

 quired to inhibit the swelling effect of the 

 acid is therefore much smaller than that 

 of NaCl.^= 



When a muscle is put into a .04 solution 

 of NajSO^ which is rendered m/200 acid 

 through the addition of H2SO4 the muscle 

 first absorbs water and later is dehydrated, 

 as the* following experiment by Beutner"'' 



CHANGE IN WEIGHT OF MUSCLE IN .04m 



Na^SO, — N/200 H^SO, 



1 hour 4- 9.9 



3 hours -H12.3 



6 hours -{- ] -8 



24 hours — 19.3 



32 hours — 25.2 



96 hours — 31.2 



The interpretation of this result offers 

 no difficulty. As Beutner pointed out, the 

 muscle obeys the law of van't Hoff, as long 

 as it is alive, or more correctly, as long 

 as the semi-permeability of its membrane 

 is preserved. Since a .04m solution of 



^Loeb, Ffliiger's Archiv, Vol. 75, p. 302, 1899. 

 Eeprinted in ' ' Studies in General Physiology, ' ' 

 Vol. II., p. 516, 1906. 



"=Loeb, Pfluger's Archiv, Vol. 75, p. 303, 1899; 

 ' ' Studies in General Physiology, ' ' Vol. II., p. 514. 



=» Beutner, Bwchem. Zeitschr, Vol. 39, p. 280, 

 1912. 



NaoSO^ is hypotonic, the muscle must ab- 

 sorb water in such a solution. As soon as 

 the semi-permeability of the muscle is lost 

 and the acid diffuses into the muscle it 

 behaves altogether differently, namely, like 

 a piece of gelatine. Proctor has shown that 

 solid gelatine swells in a salt solution as 

 well as in an acid solution, while it is de- 

 hydrated in a combination of both; and 

 the same is true for the dead muscle. 



IX. INTERNAL CHANGES IN THE MUSCLE 



Miss Cooke showed that the fatigued 

 muscle of a frog is no longer isotonic with 

 an m/8 solution of NaCl, but with a 

 3m/16 solution. The fatigue has, there- 

 fore increased the osmotic pressure of the 

 muscle.^' The writer suggested that in 

 this case lactic acid was formed and that 

 this lactic acid was the cause of the ab- 

 sorption of water by the muscle in an 

 isotonic solution.-* The lactic acid might 

 act as a catalyzer in certain reactions, 

 whereby the osmotic pressure would be 

 raised in the muscle. Others assume that 

 some colloid in the muscle is caused to 

 swell by the acid. This could only refer 

 to some solid colloid. But it is difficult to 

 understand how this could force the muscle 

 to absorb more water. Proctor^^ has 

 shown that solid colloids absorb not only 

 water, but also salts (even in the presence 

 of acid) ; if this be the case the swelling of 

 solid colloids inside the muscle can only 

 increase the osmotic pressure of the liquids 

 contained inside the muscle cells, if rela- 

 tively more water is absorbed than salt. 

 Since no quantitative data are available on 

 this point, it is useless to argue the question. 



" In order to avoid misunderstandings it should 

 be said that the fatigued muscle obeys Avogadro's 

 law, only its point of isotony is increased. 



^'Loeb, Pfluger's Archiv, Vol. 71, p. 466, 1898. 



^ Proctor, ' ' Kolloidchemisehe Beihef te, ' ' Vol. 

 II., p. 262, 1911. 



