TRANSACTIONS OF SECTION I. 895 
Bernstein and Schoenlein as well as Wedensky, who used Kronecker’s tone- 
inductorium, found that when the frequency of stimuli exceeded 1,000 per 
second, the muscle tone no longer corresponded with the frequency of stimuli, 
but a lower tone was given out. 
It seems to H. Kronecker, that the tone of the interruptor governing a 
moderate frequency of stimuli, would not only be reproduced in the muscle with the 
same pitch, but also with the same timbre and quality. 
We desired to know, whether the tones from two interruptors vibrating at 
different rates could be heard in the doubly stimulated muscle. 
The gastrocnemius muscle of the rabbit, irritated directly or through the sciatic 
nerve, was used for stimulation with opening induction shocks of different frequen- 
cies, in some cases of 60 and 100 per second, and in others of 100 and 200 per 
second. 
With the same intensity of current from both interruptors, in most instances, 
the high tone was heard in the muscle by means of a solid stethoscope, at first 
stronger than the lower tone; but the low tone remained audible longer than the 
high tone. 
In several instances, however, the low tone became inaudible before the higher 
tone. 
The same result followed if the nerve was clamped in two pairs of electrodes, 
the one proximal and the other distal. 
When the nerve was stimulated through the proximal electrodes, the tone was 
weaker than when it was stimulated through the distal electrodes, although the 
intensity of the current, and the frequency of the stimuli remained the same in 
both places. 
When the cerebrum of the rabbit had been eliminated, and the cervical cord 
stimulated with induction shocks of different frequencies, there could be heard for 
several seconds the deep natural muscle tone. 
Stimulation of the lumbar cord gave, in consequence of the spreading of 
derived currents to the nerve roots, the artificial muscle tone. 
In another similar experiment, we heard the deep natural muscle tone for 
several seconds only, When a frequency of 100 stimuli per second was used 
alone, and with the same intensity of current as before, namely 10,000 units 
(with three Daniell cells, the position of the secondary coil on a convenient scale 
of induction machine), a strong and increasing tetanus followed, and a loud and 
distinct tone was heard which increased in strength as long as the stimulus 
lasted. This note was one tone higher than that of the tuning-fork interruptor. 
The same was heard when the lumbar cord, and when the muscle itself was 
stimulated. 
In the dog whose cervical cord was stimulated we heard the deep natural 
muscle tone, as well with 100 stimuli per second as with 60. 
When the ‘action currents’ of the muscle stimulated by different frequencies were 
made audible with the aid of the telephone, the same results were obtained as 
when we listened to the muscle directly. 
The higher tone became inaudible before the lower tone. 
2. The Propagation of Impulses in the Rabbit's Heart. By H. KRONECKER 
and Dr. F.C. Busca. [From the Physiological Institute at Bern.] 
W. His, jun., has cited only one fact in support of the myogene nature of the 
adult heart pulse. 
At the Third Physiological Congress in Bern ' he communicated the observation 
that simple muscle fascicles could be demonstrated between the septum atriorum 
and the septum ventriculorum of rabbits’ hearts, and that through these fascicles, 
impulses were conducted from the auricles to the ventricles. 
_ We have, in a number of rabbits, cut through the septum atriorum near the 
septum of the ventricles, from the dorsal side of the heart where His and Romberg 
1 Centratblatt f. Physiologie, ix. p 469 
