. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 544 K. OHTSU AND M. YOSHIDA n B. q s n D n —•- FIGURE 9. Light-off responses of various types of pulses. The upper trace of A is a record from the outer nerve ring. In B, the upper trace is a record from the tentacular base and the lower trace, from the subtentacular region. In C, the upper trace is a record from the distal side of the tentacle and lower trace, from the proximal side of the same tentacle. Experiments in B and C were done on nerve ring-free preparations. In D and E, the upper traces are records on the outer n
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 544 K. OHTSU AND M. YOSHIDA n B. q s n D n —•- FIGURE 9. Light-off responses of various types of pulses. The upper trace of A is a record from the outer nerve ring. In B, the upper trace is a record from the tentacular base and the lower trace, from the subtentacular region. In C, the upper trace is a record from the distal side of the tentacle and lower trace, from the proximal side of the same tentacle. Experiments in B and C were done on nerve ring-free preparations. In D and E, the upper traces are records on the outer nerve ring and the lower ones, from the subtentacular region. The downward shift of the lower trace of A shows light-off. Arrows indicate stimulus arti- facts by light-off. The time mark in the lower trace of A shows 100 msec. B-E were swept at the same rate as A. PSP's are indicated by dots. nMP's by "n," QSCP's by "q" and SMP's by "; Vertical bar shows: 2 mV in A, D and E; mV in B and C. Ill his review, Mackie (1970) is of opinion that pacemaker function is restricted to the nervous system in hydromedusae. Since Romanes (1876), rhythmic swim- ming pulsations in hydromedusae have been known to he under the control of pacemakers around the hell margin, but direct evidence of nerve impulses is lacking. As mentioned above, we have recorded in Spirocodon two types of pulses (nMP's and PSP's) from around the nerve ring. One should be very cautious in assuming pulses taken from hydrozoans to be nervous in origin, for there is ample evidence that non-nervous epithelial pulses do occur (Mackie, 1965; Mackie and Passano, 1968; Josephson and Macklin, 1967). They are characterized by their long time course, slow conduction velocity and extensive distribution, while nervous events seem to be recorded only in the region of the nerve ring. Con- sidering the restricted occurrence to the nerve ring and also the shorter duration and. Please note that thes
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
