488 STUDIES IN GENERAL PHYSIOLOGY 



mirror, but that a moistened glass plate is just as good a 

 mirror as a metallic plate. If we were dealing with the 

 effect of waves, this would not have been the case, as electric 

 waves penetrate a thin layer of water more easily than a 

 metal plate. Secondly, the body of the experimenter can be 



used in this experi- 



O O ment instead of 



a mirror. The ex- 

 perimenter needs 

 -.. only to bring one 



* ^* - hand into the 



C o 



* neighborhood of 



FIG. 143 /T ^. 



the sphere a (-big. 



142), the other in the neighborhood of the end b of the 

 muscle preparations. In this way the muscle can be made 

 to contract, and the result might convince any believer in 

 telepathy that his superstition has a scientific foundation. 

 In the latter case the effects of induction are too apparent, 

 the effects of a reflection of waves too improbable, to allow 

 one to think of a wave-effect. 



The last series of experiments which I published con- 

 sisted in the inhibition of the electrical effects through a 

 screen. The preparation lies parallel to the spark discharge 

 and in a position symmetrical with reference to the spheres 

 of the discharger (Fig. 138). The preparation contracted 

 energetically each time the spark passed between the spheres 

 of the discharger. If now a metal screen SS 1 (Fig. 143) 

 is placed behind the preparation and parallel to it, these 

 effects disappear. This can be explained as the result of 

 induction. A distribution of the electricities will be induced 

 in the mirror by the two spheres in the same sense as in the 

 muscle preparations. Since the same kinds of electricity lie 

 opposite each other in the mirror and in the nerve-muscle 

 preparations, the effect upon the muscle preparations must 



