434 



SCIENCE 



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



purpuratiis) belongs to this type.^^ On 

 the other hand, there are membranes which 

 are neither permeable for salts nor for 

 water. This type of membranes is repre- 

 sented by the eggs of Fundulus, and ap- 

 parently Fundulus itself, and probably by 

 a large number of other aquatic verte- 

 brates. 



All these membranes are, however, per- 

 meable for gases (O, and CO,) dissolved 

 in water. 



v. THE APPARENT CONTRADICTION BETWEEN 

 THE PHYSIOLOGICAL EFFICIENCY OF 

 SALTS AND THE SEMI-PERME- 

 ABILITY OF CELL WALLS 



We will now discuss a difficulty which 

 the idea of impermeability of the cells for 

 salts has to meet. In a pure NaCl solution 

 the frog's muscle begins to twitch, while 

 the addition of a little Ca inhibits this 

 effect. It is difficult to assume that salts 

 act without diffusing into the cell, and yet 

 the phenomena of isotony are incompre- 

 hensible without the assumption of prac- 

 tical impermeability of the cell for salts 

 and sugars. This difficulty is apparently 

 relieved by the investigations of Loeb and 

 Beutner^' on the potential differences at 

 the limit between living organs and the 

 surrounding solution of electrolytes. If 

 we form a cell of the type : solution of 

 electrolyte (concentrated); living organ; 

 solution of electrolyte (dilute), the dilute 

 solution is positive towards the concen- 

 trated; and the more so the greater the 

 dilution. This seems to be a fact for most 

 living tissues. From this it follows that 

 living tissues are reversible for kations. 

 "We were, moreover, able to show that the 

 electromotive forces of such cells obey 



"Loeb, Emix's Archiv, Vol. 26, p. 82, 1908. 

 " Loeb and Beutner, Biochemische Zeitschr., 

 Vol. 41, p. 1, 1912; Vol. 44, p. 303, 1912. 



Nernst's law, according to which the 

 E.M.F. varies with the logarithm of the 

 concentration. But the most surprising 

 fact we found was that the living cells are 

 reversible in regard to practically any 

 kation, while the potential differences here- 

 tofore observed by physicists at the limit 

 of two phases were only reversible for one 

 kation. These results are only intelligible 

 on one of two assumptions: either the sur- 

 face of all living organs contains already 

 traces of all metals, which is not very prob- 

 able; or traces of the electrolytes react 

 with the surface of the living organ. If 

 the latter is true we can understand that 

 electrolytes can influence the life phenom- 

 ena and yet produce the theoretically cal- 

 culated osmotic pressure upon the walls of 

 living organs. 



The writer suggested thirteen years ago 

 that chemical reactions occur between the 

 electrolytes and certain parts of the "pro- 

 toplasm" — proteins or fatty compounds — 

 which result in the formation of ion or 

 metal-proteins or soap-like compounds, and 

 that these reactions explain the influence 

 of the electrolytes upon muscular twitch- 

 ings, heart beat, etc. It is well known that 

 the action of salts like NaCl or CaCL or 

 KCl upon the heart beat or muscular 

 twitehings is — within certain limits of con- 

 centration and time — perfectly reversible, 

 and this reversibility is characteristic of 

 this action. Such a complete reversibility 

 of chemical reactions is intelligible if only 

 traces of the salts enter into reaction with 

 the substances contained in the living 

 organ. 



Beutner reached the conclusion on the 

 basis of thermodynamical calculations that 

 the potential differences observed by us at 

 the junction of living organs and sur- 

 rounding solution demand the assumption 

 of a chemical reaction between traces of 



