154 JELLY-FISH, STAR-FISH, AND SEA-URCHINS. 
Rhythm next day (five-minute intervals). 
| 
Segment i. | Segment }. Segment } A. | Segment 3 B. 
68 | 55 17 | Dead. 
Next day all the segments were dead except the 
largest one, in which a single lithocyst still con- 
tinued to discharge at the rate of twenty-four in 
five minutes. 
Now, with regard to these tables, it is to be 
observed that during the first day the prepotent 
lithocyst in the eighth-part segment A maintained 
an undoubted supremacy over all the others, and 
that the same is true of the comparatively potent 
lithocysts in the quadrant.. (This is not the case 
with segment B; probably the degree of prepotency 
of the lithocyst in this case was not sufficient to 
counteract the antagonistic influence of the smali 
size of the segment.) But next day the supremacy 
of the small segment A was not so marked; for 
although its rhythm was more regular in the stale 
water than was that of the largest segment, its 
actual number of contractions in a given time was 
just about equal to that of the largest segment. 
Again, after transference to fresh sea-water,* the 
balance began to fall on the side of the larger seg- 
ments; for even the quadrant, which in the stale 
water had ceased its motions altogether, now held 
a middle position between that of the half-segment 
and the prepotent eighth-part segment. On the 
next day, again, the balance fell decidedly in favour 
of the larger segments, and the weaker eighth-part 
