. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. ("OX'DUCTINC SVSTKMS OI-" CORYMORPHA 247. s- -J t V 1 t t t t t FIGURE 2. Excitation and inhibition produced by single electrical stimuli; (A.) intact animal, (B.) a sheet of stalk tissue. Vertical scale equals 100 ; horizontal scale equals 5 sec. single small pulse travelling along the stalk in a non-decrementing fashion (Fig. 1C). In the majority of cases where this is the sole electrical response there is either no visible reaction or there is a slight overall contraction. At slightly higher stimulating volt
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. ("OX'DUCTINC SVSTKMS OI-" CORYMORPHA 247. s- -J t V 1 t t t t t FIGURE 2. Excitation and inhibition produced by single electrical stimuli; (A.) intact animal, (B.) a sheet of stalk tissue. Vertical scale equals 100 ; horizontal scale equals 5 sec. single small pulse travelling along the stalk in a non-decrementing fashion (Fig. 1C). In the majority of cases where this is the sole electrical response there is either no visible reaction or there is a slight overall contraction. At slightly higher stimulating voltages a hurst of pulses is usually produced (Fig. ID). Associated with this burst there is usually a more violent contraction and there may be a simultaneous oral flexion of all proximal tentacles sometimes accompanied by an aboral flaring of the distal tentacles. Some animals show a fairly clear-cut threshold for burst initiation, while in others this threshold varies. Both the intensity of contraction and the length of a stimulus-initiated burst appear to depend on the strength of the stimulus. Stimulation normally produces bursts of electrical activity (Fig. 2A) ; but it can also interrupt ongoing spontaneous elec- trical activity (Fig. 2B). Fig. 3 shows several hursts all produced by the same animal in response to single electrical stimuli. Conduction velocity in the TPS. Apparent conduction velocity in the TPS varies both within an animal over time and, to an even greater extent, between animals. There is no apparent difference in the conduction velocity as measured between two points on the stalk and between one point on the stalk and another on the hydranth. The average conduction velocity between two points on the stalk determined from a minimum of five measurements on each of ten animals was cm/sec. Individual averages varied from cm/sec to cm/sec. This average value is quite close to the average spontaneous pulse conduction velocity of cm/sec which
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
