(URS ) 
drawn av ray and the nerve itself is hit by the drops, whilst then 
the registration takes place. 
Along a somewhat sloping substratum, on which the nerve rests 
in a groove, the drops of mercury rapidly flow away. By 
changing the frequency of the drops and altering the height of their 
falling, often also spontaneously without any alteration in the external 
conditions for the experiment, all kinds of discongruencies may be 
seen to show themselves between the mechanical and electric 
reactions of the muscle. Beautifully regular curves of fatigue, are in 
this way difficult to obtain, as it is not always possible to bring 
about an always equal fall of the drops of mercury, as to frequency 
and direction. The curve in fig. 1, got in the above way, proves 
that the electric phenomenon of the succeeding contractions in the 
‘ase in question every time has the same course and the same 
amplitude. In contradistinetion to this the mechanical effect is repeatedly 
unequal. 
b. Kuperiments with the tapping hammer. 
The tetanomotor of HerIDENHAIN is thus linked in a chain with a 
chronoscope as interrupter that only twice a second the hammer 
hits the nerve in the isolated ivory groove. To preserve the nerve 
as much as possible from too rapid lesion, a bit of muscle tissue, 
to break the thrust of the hammer, is laid across under the nerve. 
The nerve itself is, by means of a little windlass, slightly strained. 
On the whole it is very difficult to regulate the fall of the tapping 
hammer and the tension of the nerve so as to make the stimuli 
every time follow by a regular series of mechanical and electric 
reactions. Now and then, however, it is possible to make a good 
series, as fig. 2 subjoined shews. 
It is seen how the series in fig. 2 begins with a large, initial, 
mechanical and electric reaction, followed by the others which are 
directly much smaller. At the same time there takes place after the 
first reaction a removal of the zero-position, first in one direction 
and then in the opposite direction. On the whole the form- and 
electromyograms are well nigh congruent. Now and again we see 
how the muscle with a compound contraction reacts upon a single 
stroke of the hammer. 
To dose exactly and administer a better, always the same, local 
stimulus, the electric stimulus was in the course of the further inves- 
tigations made use of. 
