466 STUDIES IN GENERAL PHYSIOLOGY 



A comparison of Tables XII and XI shows again how 

 much stronger the specific effect of the hydroxyl ions is than 

 that of the hydrogen ions for the absorption of ivater by 

 muscle. 



The increase in the weight of the muscle under the influ- 

 ence of dilute acids and alkalies therefore continues even 

 when the muscle has already lost its irritability. As only 

 small amounts of the acids and alkalies are used, one is 

 inclined to imagine the effect of the H and OH ions to be of 

 a fermentative character. 



V. IN HOW FAR ARE THE CHANGES IN THE WEIGHT OF THE 

 MUSCLE A FUNCTION OF DIFFERENCES IN OSMOTIC PRES- 

 SURE BETWEEN THE MUSCLE AND THE SURROUNDING 

 LIQUID ? 



1. I have availed myself of more than a hundred experi- 

 ments to show that in a 0.7 per cent. NaCl solution the 

 gastrocnemius muscle of the frog generally suffers no impor- 

 tant change in weight during the first hour. Often it loses 

 a few milligrams in weight ; in rare cases it increases a trifle ; 

 in the remaining cases its weight remains absolutely con- 

 stant. The 0.7 per cent. NaCl solution can therefore be 

 looked upon as approximately of the same osmotic pressure 

 as the total osmotic pressure of the molecules and ions dis- 

 solved in the muscle cells. The fact that the presence of an 

 acid or base in the salt solution compels the muscle to increase 

 in weight shows that we have to deal in living matter with a 

 system which alters its osmotic pressure easily, or in which 

 the permeability of the protoplasmic wall is easily modified; 1 

 One might perhaps think at first that the great increase in 

 the weight of the muscle upon the addition of acids or alka- 

 lies is simply determined by the fact that the muscle itself 



1 It is possible that the absorption of water caused by alkalies and acids belongs 

 to those phenomena of imbibition which have recently been studied by van Bemmelen. 

 [1903] 



