( 652 ) 
these oscillations were remarkably smaller and had greater latency. 
i have likewise tried to conduct the active current of the nervus 
acusticus of the frog. The nervus acusticus of this experimental 
animal can easily be reached without injuring the normal circulation 
or the brain. | have however not succeeded in observing an oscillation 
of the string-galvanometer. This may be partly attributed to the 
insufficient sensibility of the instrument, on the other hand the 
sensibility of the frog for sounds is exceedingly trifling. A frog poisoned 
with stryehnine which showed symptoms of spasms when being blown, 
did still react with muscular spasms at a shot in the immediate 
vicinity, but did not do so when the shot was ‘fired at some distance. 
Of the different tones it was those of a low vibrating figure that 
caused the greater reaction upon such like frogs, the high tones often 
had no influence at all. From the experiments of Yrrkrs *) about 
the vigorating influence of the tone on the effect of a mechanical 
irritation it appears that vibrations of 50—10000 per second, in 
some way or other, cause an irritation to the nervous system of 
the frog. 
I can moreover communicate that like Preer ®) I could show an 
electric current in a pike with the string-galvanometer when with a 
glass-rod the otolith was moved. The unpolarisable electrodes were 
placed in such a way that one of them touched the nervus acusticus 
at the parietes of the emptied skull cavity, the other stood at some 
indifferent point of this parietes. Care was taken that neither the electrode 
nor the object could move from their places. I could not observe 
any electric action caused by a sound of whatever nature that was 
conveyed by the air to the head of the pike. 
Mathematics. — “On quartic curves of deficiency zero with a 
rhamphoid cusp and a node.’ By Prof. Grorer Mascen of 
Agram. (Communicated by Prof. Jan pr Vaiss). 
1. We shall here consider the quartic curve, which has as equation 
(ma, + nere) — £,2,7 (er, br jy=0. . . . ie 
It is easy to prove, that the represented curve has a rhamphoid 
cusp in the vertex A (1,0,0) of the triangle of reference, that the 
cuspidal tangent is the side 2,=O of this triangle, and that the 
vertex B(0,1,0) is a node of the curve. The side #, =O is chosen 
1, Yerkes Journ. of Comp. neurol and Psychol XV, p. 279. 
2) Piper. Zentralblatt f. Physiol 1906 Bd. I, p. 298. 
