ADVANCED EXPERIMENTAL PHYSIOLOGY 301 



CHAPTER VI. 



EFFECT OF DISTILLED WATER AND OF VARIOUS SALTS 

 ON MUSCLE. 



THE various tissues of the body are all bathed in the same fluid, 

 the lymph, which so far as the water and salts it contains are con- 

 cerned, has a uniform composition. The tissues, although immersed 

 in the same fluid, show different and characteristic properties owing to 

 their difference in structure and chemical composition. If, however, 

 the composition of the fluid, in which any given tissue is immersed, be 

 altered, the composition and consequently the properties of its proto- 

 plasm must also be altered. The first effect on living matter of such 

 a change is to cause its stimulation, and then if the change be 

 sufficiently profound and long-continued to produce its death. 



Only two changes in the tissue fluids will be considered here, 

 namely (a) Gross change in the osmotic pressure of the fluid, by 

 using distilled water or a strong saline solution ; and (b) Change in the 

 ions in solution without alteration in the osmotic pressure of the fluid, 

 by using solutions of various salts isotonic with frog's blood -plasma. 



Effect of Distilled Water. Dissect out a gastrocnemius muscle and 

 place it, without a 'trouser' of skin, in a watch-glass containing 

 distilled water. For a few minutes the muscle may show irregular 

 contractions, then it becomes opaque, swollen and incapable of re- 

 sponding to a stimulus with a contraction. The muscle is said to have 

 passed into a condition of 'water-rigor.' Test the muscle with induction 

 shocks and demonstrate that it will no longer contract. 



By placing the muscle into distilled water two effects are produced 

 the inorganic salts in the muscle diffuse out into the water, and water 

 is attracted by osmosis into the muscle so that each fibre becomes 

 greatly distended with fluid. The first effect of these changes is to 

 produce stimulation, but, as the muscle fibres are distended with fluid, 

 they become incapable of contracting, and finally there are not enough 

 salts left in the muscle to keep the globulins in solution ; hence the 

 muscle becomes gradually opaque and dies. 



Effect of Strong Saline Solutions. This effect will be exactly the 

 opposite of that due to distilled water ; for water will be abstracted 

 from the tissue, and large quantities of the salt will diffuse into the 

 muscle. 



The effect on a tissue of mere abstraction of water from it is best 

 seen by allowing a nerve to dry. Make a gastrocnemius and sciatic 



