ACTIVITIES OF COLONIAL ANIMALS 499 
wave that had been observed to start from the given end was now 
seen to be more than half-way across the strip and progressing 
uninterruptedly toward the farther end notwithstanding the fact 
that it had been passed over by a wave of phosphorescence. ‘The 
passage of these two waves, one rachidial and the other phos- 
phorescent, on the same band of tissue and in a way so that one 
overtook and outran the other without, however, interfering 
with it, affords a strong argument in favor of their independence. 
The rate at which the wave of luminosity passes over the rachis 
of Renilla, 7.39 em. per second, was determined in sea-water at 
a temperature of 21°C. To ascertain whether this rate is influ- 
enced by changes of temperature, two sets of determinations were 
made, one at 11°, 21°, and 31°C., and another at 15°, 20°, and 
25°C. These temperatures were maintained by immersing the 
strips of rachis pinned out on wax in large vessels of sea-water 
at the desired temperature. In the initial set the readings were 
taken first at 21°, then at 11°, next at 31°, and finally as a check 
at 21° again. In the second set the sequence of temperatures 
was 15°, 20°, 25°, and 15°C. In both instances the rate char- 
acteristic for the first test was recovering after the tissue had been 
subjected to lower and higher temperatures, showing that these 
temperatures had not of themselves caused any permanent. alter- 
ation in the tissues. The results of these two sets of tests are 
given in tables 5 and 6. 
In the first set of determinations (table 5) the average rate per 
second at 11° was 4 em.; at 21°, 7.6 em., and at 31°, 20.7 cm. 
In the second set (table 6) the average rate per second was at 
15°, 6.5 cm.; at 20°, 8.3 em., and at 25°, 12.2cm. The relations 
of these records can best be seen in figure 12, where the two 
groups are plotted independently. As these plottings show, the 
two sets of determination lie close together and are reasonably 
conformable. Their relations are better expressed by slightly 
curved lines than by straight ones. As is shown in the shorter 
set, an increase of 10° in temperature is accompanied by an 
approximate doubling of the rate, 6.5 em. to 12.2 em. per second. 
Judging from the curve itself, the same appears to be true of the 
longer set except for its upper range. If in this set the rate per 
THE JOURNAL OF PXPERIMENTAL ZOOLOGY, VOL. 31, No. 4 
