538 EDWARD B. MEIGS 



The osmotic properties of striated muscle 



My experiments with striated muscle confirm Overton's results 

 with striated muscle except in the case of the action of isotonic 

 KCl solutions. My results show that the weight of living striated 

 muscle immersed in an isotonic KCl solution may increase 50 

 per cent; from which it follows that the surfaces of the living stri- 

 ated muscle fibers are quite permeable to KCl. The experiments 

 with half strength and double strength Ringer solution, add to 

 the already existing evidence for the view that the striated fibers 

 are surrounded by semi-permeable membranes. They show that 

 living muscle immersed in non-isotonic solutions gains or loses 

 weight in such a manner as to suggest that osmosis plays the 

 chief part in the early stages of the process. 



While the evidence for the view that the surface of the striated 

 muscle fiber is relatively impermeable to salts and sugars is very 

 strong, there are equally strong reasons for believing that both the 

 permeability of the surface and the osmotic pressure of the con- 

 tents of the fiber are subject to variation. Some of the reasons 

 . for holding this view have already been given in the introduction, 

 and my own experiments add still further to the evidence for it. 

 The curves of figures 3, 4, 5 and 6 which show how striated muscle 

 gains weight in half strength Ringer solution and loses weight in 

 double strength Ringer vsolution, indicate that the osmotic pres- 

 sure of the contents of the muscle fibers is subject to variation. 

 It is to be noted that only the beginnings of these curves are of 

 such a character as to suggest that the water intake or outflow 

 is an osmotic process. After the first twenty or twenty-five min- 

 utes the curves representing these processes become nearly straight 

 lines — the muscle absorbs or gives out equal quantities of fluid 

 in equal periods of time. 



It may readily be supposed that the initial osmotic intake of 

 water from a hypotonic solution by the muscle and the consequent 

 dilution of the salts within the fibers cause the muscle colloids 

 to combine slowly with water. The water entering the muscle 

 fibers would, therefore, combine with the colloids about as fast 

 as it came in, the salts dissolved in the inorganic water would be 

 maintained for some time at about the same concentration some- 



