278 JOURNAL OF COMPARATIVE NEUROLOGY. 
The length of nerve-cord between the points of stimulation 
was measured after the preparation was killed in fresh water, in 
which the condition is very near the normal extension of the 
worm. 
EXPERIMENT NO. 2, Table X, postero-anterior, Aug. 7, Igor. 
Distal Proximal 
No. of records 8 9 
Mean latent time 0.095 sec.| 0.061 sec. 
Standard deviation 0.003 sec. | 0.0046 sec. 
Coefficient of variability .031 -075 
Length of cord: 55 cm. (45 segments). 
Rate: 165 cm. per sec. 
TABLE X. 
Summary of experiments on WVerezs sp. 
Postero-anterior rate. 
No. on ie No: of records Length of ’ 
j : ; : Rate in cm. 
experiment Distal Proximal cord in cm. 
1 A 4 4 10.0 164 
2 8 8 5:5 165 
31 9 9 12.0 223-2 
4 3 3 5-0 156.0 
5 4 4 120 | 123.6 
Mean rate: 165 cm. per sec. 
Standard deviation: 32. 
Coefficient of variability: .19. 
Nereis virens Sars (=N. branti Ehlers). 
This species seems to be quite rare at Pacific Grove, since 
but one specimen was secured during extended collecting in 
the summers of 1901 and 1902. The specimen was about 100 
cm. in length and from 1 to 1.5 cm. in diameter, but it unfor- 
tunately broke into several pieces through its contractions when 
being captured and the piece containing the head, which was 
the largest, broke up further in attempting to submit it to the 
experimental conditions. Decapitation served to quiet its mo- 
tions, and, no doubt, a much. longer portion could have been 
obtained if this treatment had been used at first. The ventral 
cord was from I mm. to I.5 mm. in diameter, which large size 
together with its favorable position in the body allowed it to be 
easily dissected free. Two pieces were used, one with the 
head contained 85 segments and gave an available distance of 
cord of 20cm. The other was from near the tail and con- 
tained 25 segments with 6.5 cm. of cord available. These dis- 
