JENKINS AND Carson, Nervous lmpulse in Worms. 265 
EXPERIMENT No. 1, Table I, Dec. 26, 19QI. 
Distal Proximal 
No. of records 6 6 
Mean iatent time 1.76 sec. 0.29 Sec. 
Standard deviation 0.174 sec.| 0.06 sec. 
Coefficient of variability 10 .20 
Length of cord: 8cm. Rate: 5.44 cm. per sec. 
TABLE I. 
Summary of experiments on Cerebratulus sp. _Postero-anterior rate. 
No. of No. of records Length of | Ry 
experiment Distal Proximal cord in cm. ateia eu. 
: 2 8 5-44 
= 5 5 5 | 9.0 
Aulastomum lacustre. 
(Horse Leech.) 
Through the kindness of Mr. J. C. Brown of the Depart- 
ment of Animal Biology of the University of Minnesota, we re- 
ceived a number of large individuals of this species from Lake 
Vermillon, Minn. They thrived well in the aquarium, some 
kG 
AVAVAVAVAVAVAVAVAVAVAVAVAVAVAVAVAVAVAVAVAVAVAVAVAVAVAVAVAVAVAVAVAVAVAVAVAVAVAVAN 
Fig. 2. Aulastomum lacustre, Postero-anterior. Length of nerve cord between 
distal and proximal electrodes: 11cm. Rate: 63.8 cm. persec. Time: 
50 d.v. per sec. 
being kept for over three months. The preparations used may 
be therefore regarded as from individuals in good condition. 
