(426) 
§ 2. Electrical stimuli. 
As electric stimuli were used the opening- and closing-currents 
either of a faradaic or of a galvanic current, which was interrupted 
either by means of an interrupter fixed to KaGrnaar’s chronoscope 
of */, second with swinging platina-contacts, or by means of the 
rheotome-apparatus of ENGELMANN connected with a kymographion. 
With this rheotome-apparatus the stimuli were on the whole less 
frequent and the contactstoppers were placed so as to make the 
closing- and opening-stroke follow each other with well nigh equal 
intervals of 2 seconds. The following objections, however, can be 
raised to these methods of stimulation. In the course of the process 
of fatigue the muscle sooner or later, owing to the weight to be 
raised, the size of the stimulus, its frequency and the previous history 
of the muscle itself, comes into such a condition that the muscle is 
perhaps still potentially able to execute contractions, but is accidentally 
prevented from doing so by tetanus respectively tonus. Further we are, 
especially with the rheotome-apparatus, at which the stimuli as a 
rule cannot nearly be deemed equivalent, not entitled to make 
comparisons between the respective mechanical and electrical reactions 
at different periods of the process of fatigue. Therefore another series 
of experiments was made, in which the muscle, it is true, in the 
manner described just now was tired by means of opening- and 
closing-stimuli of a constant current, but in which during the 
whole course of this process of fatigue the muscle was at regular 
intervals examined in its mechanical and electric reactions by means 
of a single closing-induction-stroke. Every time, however, before 
this closing-induction-stimulus was administered, the muscle was 
first allowed to become pertectly lax. In making the experiment 
a Ponr-swing without a connecting cross was made use of, by 
which the nerve could be stimulated at will, either by the periodical 
interruptions of the constant current, or by the single elosing- 
stroke, obtained by the falling-apparatus of BERNSTEIN, in the 
primary chain of an inductorium. The usual provisions were made, 
see GARTEN '), to prove that the electric phenomena do not originate 
in artificial current-loops. 
As a demonstration I give here a short review of one of the 
experiments from the last series. 
Brains and spinal marrow of a Rana fusca have been destroyed. 
The M. gastrocnemius, arranged for the experiment in the above 
manner, is stimulated indirectly, alternately with a breaking galvanic 
1) Garren S. Elektrophysiologie. Handbuch der Physiologische Methodik p. 470. 
