424 GUSTAF FR. GOTHLIN 
greater than three per second (> 180 per min.). On one occa- 
sion, however, the frequency sank so that it became possible to 
count. The frequency was then 40/23 sec. = 104 per min. 
In the case of animals that took up a vertical position at the 
bottom of the aquarium with the oral pole downward and had, 
as far as the eye could judge, the same rapidity of ciliary motion 
in all the rows, it was observed that if one varefully moved them 
to a horizontal position they rose again into a vertical position, 
generally by decreasing the rapidity of the ciliary motion in the 
lower rows. Whether in my experiments there was also an accel- 
eration of the frequency in the rows on the upper half of the body 
compared with that of the vertical position, as Verworn describes 
(91, p. 448) I cannot venture to decide, as this change of position 
was only observed in individuals that had so rapid a ciliary 
motion even in the vertical position that the number of waves 
could not be counted with certainty with the eye and a stop- 
watch. 
12. A Beroé 18 mm. long began to be observed in the aquarium 
at a temperature of 14°C. on the 30th of July at 10 h. 30 m. a.m. 
It remains at the bottom of the aquarium, has a normally rapid 
ciliary motion, and on some occasions shows spontaneous stop- 
pages lasting for a few seconds. The animal is transferred to a 
cuvette at 10 h. 42 m. . 
10 h. 45 m. By touching the circumference of the animal’s 
mouth with a smooth round glass rod a total stoppage lasting 
2.5 seconds is caused without any drawing in of the rows. Tem- 
perature in the cuvette, 15.7°. 
10h. 48 m.—11 h. 38m. As long as the animal is in the usual 
horizontal position the rows on the lower half of the body strike 
with a slower frequency than those on the upper half, no matter 
which half of the body is turned downward. On one occasion 
the animal took up such a horizontal position that the meridian 
through the points of the polar fields became vertical. Even in 
this position the ciliary activity on the lower half of the body was 
slower than that in the upper part. 
11 h.40m. For the purpose of narcosis the animal was trans- 
ferred into a cuvette containing sea-water with a 0.1 per cent 
