268 JOURNAL OF COMPARATIVE NEUROLOGY. 
ever, reacts well to stimuli to different points in the cord and 
allows the determination of a postero-anterior rate. On first 
making the preparation the head end contracts strongly, but in a 
few minutes it relaxes, and afterwards the preparation is fairly 
quiet, reacting only to the stimulus from the electrodes. A 
single induced shock applied to a point in the posterior portion 
of the cord usually produced contractions in its immediate vi- 
cinity which extended a short distance only, not reaching the 
head. However, a weak interrupted current of short duration 
produced a contraction which reached the anterior end. 
The preparations fatigue quickly, so that only a few com- 
parable tracings can be obtained in each case. 
The length of the nerve cord was measured in the prepara- 
tions after being killed in fresh water. 
EXPERIMENT No. 4, Table [II, postero-anterior, Aug. 16, 1901. 
Distal Proximal 
No. of records 3 3 
Mean latent time 0.28 Sec. 0.17 sec 
Standard deviation 0.009 sec. 0.01 sec. 
Coefficient of variability .03 .05 
Length of cord 10 cm. (105 segments). Rate: 90.9 cm. per sec. 
TABLE III. 
Summary of experiments on Czrratulus sp. 
Postero-anterior rate. 
No. of No. of records Length of : 
. = . Rate in cm. 
experiment Distal | Proximal cord in cm. 
I 3 | 3 13 85.8 
2 6 | 8 15 82.5 
3 4 4 18 86.4 
4 3 3 10 90:9 
5 2 5 9 99.9 
6 4 4 9.5 86.4 
Mean rate: 90 cm. per sec. 
Standard deviation: 1.66. 
Coefficient of variability: .o13. 
Arenicola sp. 
This worm as judged by the number of its egg masses seen 
during the breeding season is common in the vicinity of Pacific 
Grove. However, the sand in which it lives is so filled with 
large rocks that it is difficult to collect it. Only three work- 
able specimens were obtained. It is very sluggish in its move-. 
Ee 
