PRIMARY INHIBITION OF CILIARY MOVEMENT 431 
farther and finally over the whole row. A similar state of af- 
fairs was seen in experiment 6 under the influence of ethyl ether 
and was indicated by the fact that the number of waves was 
greater near the aboral pole than in the neighborhood of the 
oral pole. It is true that in my experiments 3 and 6 another 
possible explanation is present, namely, that the strength of the 
inhibitory impulse itself might be greater at the oral than at the 
aboral part of the row, but in the case of experiment 3 such an 
explanation would scarcely fit in with the fact that the inhibi- 
tory effect of the electric current proceeds from the cathode. It 
seems to me therefore more probable that the difference in the 
strength of the inhibition or the after effect of the inhibition, 
respectively, in different parts of the row in experiments 3 and 6 
is due to the fact that the automatism of the swimming plates is 
more pronounced in the aboral part of the row than in its oral 
part. 
When in experiment 10, a cathodic inhibition of the move- 
ments of the swimming plates could be shown in a piece of row 
cut out together with the tissue lying immediately below, but, on 
the other hand, no cathodic inhibition could be observed in iso- 
lated swimming plates, then there are the two following possi- 
bilities of an explanation of the primary inhibition on electrical 
stimulation. Either the cathodic influence extinguishes or weak- 
ens, respectively, the direct transmission in the neuroid connec- 
tion that exists between each plate and the adjoining plates in 
the row or else the neuroid conductive path between the sepa- 
rate plates or the plates themselves are under the influence of a 
primary inhibitory apparatus which can be stimulated by an 
electric current. 
It seems to me possible to come to a decision between these two 
alternatives on account of the observations made as to the pri- 
mary inhibition caused by mechanical and chemical stimulation, 
respectively, in Beroé. The slight touching of the edges of the 
mouth which in the experiments resulted in a primary inhibition 
of the meridional rows can scarcely in any, purely mechanical 
way or directly at all constitute any obstruction to transmis- 
sion between the separate swimming plates in the row. Nor can 
