DIZ G. H. PARKER 
9. Rachidial peristalsis raises Renilla out of the sand and dis- 
tributes the fluids contained within its body. It is not concerned 
with effective locomotion. 
10. Renilla is naturally highly phosphorescent at night but 
not so by day. At night its phosphorescence can be reduced by 
exposing it to light and by day this can be developed by putting 
it in the dark. 
11. Renilla is excited to phosphoresce only by stimulation, 
particularly by applying mechanical or electrical stimuli. Con- 
centric waves of phosphorescence emanate from the spot stim- 
ulated. 
12. Phosphorescence is limited to the upper surface of the 
rachis of Renilla and is produced by the masses of whitish mate- 
rial that surround the siphonozodids and the bases of the auto- 
zooids. 
13. The waves of phosphorescence pass around any form of 
incision made on the rachis. 
14. The impulses for phosphorescence are transmitted by the 
non-phosphorescing peduncle as well as by the phosphorescing 
rachis. 
15. The impulses for phosphorescence are temporarily inter- 
rupted by magnesium sulphate. At 21°C. they have a rate of 
about 7.4 ecm. per second. Between 10° and 25°C. this rate 
doubles for each increment of 10°. At 31°C. it is more than 
double that at 21°C. 
16. The autozodids of Renilla are stimulated with: difficulty 
mechanically, with ease electrically. They are not centers from 
which impulses pass freely to the rest of the colony, though they 
are easily entered by impulses from other parts of the colony. 
17. Their general withdrawal, due to stimulation of peduncle 
or rachis, spreads over the colony in a wave which may be tem- 
porarily interrupted by magnesium sulphate and which has a 
rate of 7.8 cm. per second. 
_ 18. Peduncular peristalsis and rachidial peristalsis consist of 
muscular waves whose rhythm is probably myogenic in origin. 
Phosphorescence, the withdrawal of autozodids, and general con- 
