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electric stimuli have to be considered. The stimulation takes place 
indirectly with the M. gastrocnemius of Rana. The electric and 
form-changes are registered by means of photography. The muscle 
is with the knee fastened to a substratam; the M. gastrocnemius 
is prepared free from the other muscles, whilst the Achilles-tendon 
by means of a thread is connected with a small lever bearing 
a counterpoise which is moved up and down at every muscular 
motion along a pulley. The muscle acts at a distance of 2,6 cm. 
and the weight to be lifted at a distance of 5 cm. from the ful- 
crum of the lever. The long lever-arm moves past the slit of the 
registration-box and thus throws a shadow on the sensitive paper 
of the registration-box, while at the same time the string-movements 
and the time-writer are photographically registered. The M. gas- 
trocnemius is carefully kept free from the other muscles to avoid 
the influence of the contractions and electric phenomena of the 
other unencumbered muscles. The M. gastrocnemius is led to the 
string-galvanometer by means of the unpolarizable magazine-electrodes 
with moveable cotton-seeds. One electrode usually finds itself on 
the thickest part of the muscle, while the other is placed more 
proximally. In the last series of experiments the electrodes-seeds 
with an alteration in SAMOIJLOFFs manner, were, by means of a 
thin thread, drawn through the muscle-fascia, fixed to the surface 
of the muscle, in order to be sure that always the same points 
were led to the string-galvanometer. 
§ 1. Mechanical stimuli. 
The mechanical stimuli have been obtained in one series of 
experiments by falling drops of mereury from the mercury dripping 
apparatus of ScHAFER*), whilst in another series of experiments the 
tapping hammer of the tetanomotor of HeIDENHAIN produces the 
mechanical stimulus. 
a. Mwpernnents with falling drop of mercury. 
SCHAFER’S apparatus is placed in such a way that at first, the 
drops are let fall on a sheet of glass, inserted between nerve 
and opening of the drip-tube. At a given moment when a some- 
what regular dripping has been obtained, the sheet of glass is 
1) Scudrer., E. A. A. Simple apparatus for the mechanical stimulation. Pro- 
ceedings of the physiol. Society. Jan. 1901. 
