PRIMARY INHIBITION OF CILIARY MOVEMENT 415 
counted and in addition a few that die out on the way. On the 
lowest rows the incomplete waves are considerably greater in 
number than the complete ones. 
4h.52m. The most frequent row now shows a total of 30/26 
= 69 waves per minute. 
5 h. 10 m. At present so many rows are striking and they 
strike so regularly and effectively that the animal is driven for- 
ward in the cuvette. Single inverse waves issuing from the oral 
pole are, however, also observed. 
6h. Except for occasional slight contractions of the body, the 
animal seems to be in a normal condition: it has a regular ciliary 
motion and alters its position in the cuvette. The animal thus 
seems to have grown accustomed to the prevailing concentration 
of ether. 
7. 9/7. Beroé, 20 mm. long. In the aquarium, the animal 
stays at the bottom, mostly.in a horizontal position, the fre- 
quency of the waves being 100 to 170 per minute; the tempera- 
ture is 16° at 5h. 40 m. 
5h. 46m. The animal is transferred to a cuvette containing 
sea-water to which has been added sulphas atropicus in the pro- 
portion of 1:1000. 
5h.47m. The animal has a more rapid ciliary motion than 
just previously; the frequency of the waves in one row is 20/5.5 
sec. = 218 per minute. Temperature, 17.5°. 
5h.51m. The animal begins to carry out spasmodic contrac- 
tions, during which it is deformed by partial drawing in of the 
meridional rows. 
5h. 55m. Electrodes are immersed into the cuvette. Sub- 
sequent observations are made on closure of a longitudinal oro- 
central current. 
5h. 59m. Current of density 0.35 m.amp./em.?; no inhibi- 
tion occurs. 
6 h-6 h. 7 m. Current of density 1.42-2.17 m.amp./cm.?; 
no primary inhibition occurs, but certainly a secondary one, 
caused by the animal’s retraction of the rows some moments after 
the closure of the current. Where this retraction is not suf- 
ficiently intense the ciliary motion goes on continuously at an 
exceedingly rapid speed. 
