ZOOLOGY: G. H. PARKER 
439 
internal pressure is much increased, they will contract vigorously and 
discharge more or less of their contents. The slightly contracted state 
of the excised tentacle is therefore not due to lack of pressure. It is 
also not due to the absence of inhibitory influences from the rest of the 
animal, for, if an attached tentacle is partly cut into at its base, it ex- 
hibits the same partial contraction that the excised tentacle does. It is 
highly probable that the incomplete expansion of severed tentacles is 
due to the operative complications which are involved in cutting it and 
which induces a heightened tonicity in its musculature. 
When an excised suspended tentacle is stimulated mechanically 
or by the application of weak acetic acid, mussel juice, or a weak solu- 
tion of quinine, appropriate responses are called forth that differ from 
those of the attached tentacles only in that they are feebler and less 
precise. As this modified form of response is also noticeable in attached 
tentacles which by previous stimulation have been partly contracted 
before the particular stimulus was applied, it is believed that the feeble- 
ness and lack of precision in the reactions of the excised tentacles is due 
to their partly contracted condition and not, for instance, to the loss of 
central influences. Since the excised tentacles exhibit a range of re- 
sponses like those of the normal ones except in so far as operative con- 
ditions modify them, it seems clear that the tentacles of sea-anemones 
must contain within themselves the neuromuscular mechanism essential 
to their activities as originally suggested by von Heider. 
When various stimuli are appHed to the ectoderm of an excised tentacle, 
they are followed quickly by a muscular response. When they are 
applied to the entoderm of a tentacle by being injected into its interior, 
they are also followed by the same form of response but only very slowly. 
This slowness in reaction is beheved to be due to the non-receptive 
character of the entodermal surface and to the necessity for the stimu- 
lating material to the wall of the tentacle before it can reach the receptive 
ectoderm on the outside. Such a transfusion has been demonstrated in 
the case of weak acetic acid. 
The tentacles of Condylactis like those of other sea-anemones, exhibit 
polarity. Their cilia beat always from the base of the tentacle towards 
its tip. If the tentacle is stimulated mechanically at a particular spot, 
the resultant muscular activity spreads from the stimulated spot almost 
exclusively toward the base of the tentacle. The ciHary polarity is 
unaffected by anesthetics, but that of the muscles largely disappears 
under such treatment. The muscular polarity seems, therefore, to 
depend upon a nervous condition and is probably due to the fact that 
the majority of nerve-fibers from the ectodermal sense-cells extend 
