422 GUSTAF FR. GOTHLIN 
2h.35m. The same plate continues to strike rapidly without 
any current. A current of 0.7 m.amp. (density approximately 
1.9 m.amp./em.*) is closed, but during an observation of 10 sec- 
onds there is no inhibitory effect at all on these vibrations. 
10. Experiment carried out 19/6 1913 and described in an 
earlier work by the author (717, p. 535). 
From a 50-mm. long Beroé, caught the same day, there is cut 
from a spontaneously moving row in its aboral half a piece 10 
mm. long and also some of the underlying gelatinous substance. 
There are twenty-one swimming plates on the piece of row in 
question. The preparation is placed in a circular glass vessel 
measuring 33 mm. in diameter and 9 mm. in depth; this contains 
sea-water. In the extension of the piece of the row are placed 
the two clay points from two Du Bois-Reymond unpolarizable 
electrodes. The source of the current consists of dry elements: 
with two elements the strength of the current in the circuit is 4 
milliamperes, with five elements it is 11.5 milliamperes. The 
direction of the current can be altered by means of a commutator. 
The piece of the row that was cut out shows at first no spon- 
taneous ciliary motion, but is affected exceedingly easily by 
mechanical stimulation. The least motion in the liquid causes 
vibration. Gradually spontaneous vibration begins to appear, 
with ciliary waves which have the same direction in relation to 
the row as they showed in the natural position. After sponta- 
neous ciliary action had gone on for a short while the following 
experiments were carried out. 
With two elements. The cathode is placed beyond the end of 
the row that was facing the animal’s sensory pole when in the 
natural position. At a time when the ciliary frequency is from 
two to three a second, the current is closed. After a few waves 
the swimming plates stop, first in the half that is situated nearest 
to the cathode, then in the whole preparation; the circuit is then 
broken. After ashort pause the commutator is reversed and the 
current closed. An inhibitory effect is then observed only in 
the three or four swimming plates that now le nearest to the 
cathode. 
