450 THE FUNCTIONS OF CROSS-STRIATED MUSCLES 



In practicing any particular movement therefore we are striving to bring 

 about in our central nervous system such a combination of physiological fac- 

 tors as will accomplish the desired effect. The more complicated a movement 

 is, the more difficult it is of course to discover this combination. But after 

 the connection has once been established, the movement can be carried out 

 with the greatest ease in almost a purely mechanical manner. 



Here comes in another peculiarity. When we practice a particular move- 

 ment for the first time, we use a number of muscles which have no impor- 

 tance whatever for the movement intended, but rather interfere with it, since 

 they fatigue the body to no purpose. The further the practice is carried, 

 however, the more we learn to suppress these useless movements; and at the 

 same time the respiration and circulation become more and more exactly 

 adapted to the actual needs. It has been observed that the increase in com- 

 bustion from a given additional amount of work becomes steadily less (down 

 to a certain limit), as practice continues. 



REFERENCES. W. Biedermann, "Electro-Physiology," translated by Welby, 

 New York and London, 1898. R. Du Bois-Reymond, " Spezielle Muskelphysiolo- 

 gie und Bewegungslehre," Berlin, 1903. A. Pick, " Mechanische Arbeit und 

 Warmeentwickelung bei der Muskeltatigkeit," Leipzig, 1882. A. Mosso, " Fa- 

 tigue," English edition by Margaret and W. B. Drummond, New York and 

 London, 1904. 



