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ZOOLOGY: G. H. PARKER 
by the retraction of the animal as a whole. It thus appears that the 
connections between the surface of the sea-anemone and the deep seated 
muscles concerned with retraction are so numerous and devious that a 
nervous network is the only basis of explanation. That this nervous 
network is not equally developed in all parts of the animal's body is 
seen from the fact that when a sea-anemone is cut vertically in two 
except for the lips, it is very difficult to get a retraction in one half of 
the body when the stimulus is applied to the other half. The lips are 
poor means of transmission compared with other parts of the body. 
Notwithstanding the generally diffuse condition of the transmission 
system in Metridium, there is evidence also for a certain degree of special- 
ization in the parts concerned. Stimulation of the tentacles by mussel 
juice calls forth a gaping of the oesophagus (contraction of the transverse 
mesenteric muscles) and by weak hydrochloric acid a retraction of the 
oral disc (contraction of the longitudinal mesenteric muscles). These 
two forms of response afford good ground not only for the assumption 
of independent receptors but of relatively independent transmission 
tracts, a first step in the kind of differentiation so characteristic of the 
nervous organization in the higher animals. 
The extended paper will be published in the Journal of Experimental 
Zoology. 
THE RESPONSES OF THE TENTACLES OF SEA-ANEMONES 
By G. H. Parker 
ZOOLOGICAL LABORATORY OF THE MUSEUM OF COMPARATIVE ZOOLOGY 
AT HARVARD COLLEGE 
Received by the Academy, June 1 , 1916 
As long ago as 1879 von Heider announced that tentacles severed 
from a sea-anemone were capable of much the same range of activities 
that these organs exhibit when normally attached to the animal. This 
statement has been variously accepted or questioned by subsequent 
workers. Favorable material for testing its validity was found in the 
Bermudian sea-anemone Condylactis. The tentacles of this form may 
measure as much as 15 cm. in length and may have a basal diameter 
of 1.5 cm. Severed tentacles from Condylactis contract and remain so 
for some time. They can be brought to a state of least disturbance by 
suspending them on a metal hook in seawater. Under such circumstances 
they can be inflated by gently running seawater into them till they 
attain about two-thirds their ordinary length. In this condition they 
are under a pressure of not over a few millimeters of water. If this 
