JENKINS AND Carson, Nervous Impulse in Worms. 287 
is called in question by ApAtTuy’s work. On histological 
grounds we cannot therefore say whether the ventral nerve cord 
contains such a direct nervous path extending throughout its 
whole length. 
Nor does the present work furnish anything conclusive on 
this point. It is true that the muscle-nerve-cord preparations 
of Bispira, Glycera, Eunice, Nereis and Lumbriconereis re- 
spond to a single induced shock of low intensity ; and these re- 
sponses on stimulating the cord 20 to 30 cm. from the muscle 
in Bispira and Glycera approached the uniformity of the re- 
sponses of the frog’s gastrocnemius on stimulation of the sciatic 
nerve. And such uniformity in the response to single induced 
shocks has not been found to obtain in the vertebrates when 
complex nervous mechanisms are involved. On the other 
hand, such great variation of the rate in the same preparation as 
was observed in Lumbriconereis (page 281) can not be recon- 
ciled with the physiology of simple muscle nerve preparations 
as it is known in vertebrates and molluscs. In Cerebratulus, 
Aulastomum, Cirratulus, Arenicola, and Aphrodite the muscu- 
lar response to a single induced shock applied to the nerve cord 
subsides few centimeters in either direction from the point of 
stimulation. It requires a series of shocks to obtain the mus- 
cular response if the length of nerve cord involved comprises 
many segments; which fact suggests a complex nervous path. 
But while the response of the nerve cord toa single induced 
shock points in some species to a complex, in others to a sim- 
ple nervous mechanism, the question remains yet undecided 
whether in the latter cases the nervous part of the muscle-nerve- 
cord preparation is as simple as that of an ordinary muscle- 
nerve preparation. 
It is of some interest to know that the lowest rate in the 
Annelids, that of Aphrodite, or 54 cm. per sec., is higher than 
the rate in the pedal nerve of the slug, Ariolimax, which we 
found to be 40 cm. per sec., while the rate in Glycera (430 cm. 
per sec.), Eunice (460 cm. per sec.) and Bispira (694 cm. per 
sec.) is as high and even higher than the rate in the pallial 
nerve of the swift moving Loligo (17, 1903). 
