ACTIVITIES OF COLONIAL ANIMALS 501 
trols the phosphorescence of Renilla with the burning of a trail 
of gunpowder rather than with some form of transmission of a 
purely physical type. 
RESPONSES OF AUTOZOOIDS 
The autozodéids of Renilla are for the most part relatively large 
polyps scattered to the extent of several hundred over the superior 
surface of the rachis of the colony. When fully distended they 
25 
20 
(e) 10 20 30 40 
Fig. 12 Plottings of the rates of progression of the luminous waves on mar- 
ginal bands from the rachis of Renilla as influenced by temperature. Ordi- 
nates represent centimeters per second; abscissae centigrade degree of tem- 
perature. Plotting A is taken from table 5, plotting B from table 6. 
may rise 5 to 6 mm. above the level of the rachis and may have 
a diameter of as much as 14 mm. They are delicately trans- 
parent and their mesenteries are easily visible through their 
outer walls. At the distal end each autozodid has an elongated 
mouth, the axis of which, as already stated, is related to a struc- 
tural axis of the colony as a whole. When the zodid is fully 
expanded the mouth is seen to be surrounded by white lips 
from which eight rays pass out corresponding to the mesenteries 
within and bounding the bases of the eight tentacles. ‘These 
