104 



PRACTICAL PHYSIOLOGY 



p. 84, when a " striker " 

 passes over the naked wire, 

 there is both a make and 

 break of the primary circuit ; 

 consequently in these experi- 

 ments the muscle really re- 

 ceives four induction-shocks, 

 of which, according to the 

 position of the secondary coil, 

 all four might be individually 

 subminimal, or the two break- 

 shocks might be alone effec- 

 tive, or all four might be 

 effective. In order to deal 

 with the summation of two 

 break-shocks alone, it is usual 

 to perform these experiments 

 with a special piece of appar- 

 atus, the spring-myograph or 

 the pendulum myograph. 



CHAPTER VII 



! 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 concerned, 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 com- 

 position. 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 



