リンドウ シンコウハ ニヨル スイリョク ハッセイ ノ カノウセイ ニツイテ III

In the previous report, using a carp as the experimental material, the impossibility of bringing forth the thrusting-power through the motions of the slowly opening and quickly shutting scale-plates was ascertained from both the biological and physical points of view. Namely, it was ascertained that no opening and shutting motions of the scale-plates themselves were to be brought out by the wiggling motion of the fish-body, but a sort of sliding of the scale-plates was to be brought forth along the fish-body-axis. Moreover, in this case, the flowing current on the fish-body was noted to be a sort of laminar flow, with no exfoliation accompanied. From this, in the present study, the sliding of the scale-plates was especially brought under investigation; Namely, making use of a cineprojector and a stroboscope, the wigglingmotion of the swimming fish (Tilapia nilotica, the full length 26 cm, the body height 10 cm) was examined, with the ascertainment that the forward and backward sliding-motion was a simple harmonic motion and not a slowly backing and rapidly dashing motion. In contrasting to the model-scale-plates making the slowly opening and quickly shutting motion, another model-scale-plates making the simple harmonic, forward and backward sliding motion was made by the author; and, with the use of aluminum powder, the flowing current on the scale-plates-surface was put into visualization; and, using the pressure transducer, the dynamical pressure of the fluid at the rear tip of the scale-plates was measured. Consequently, contrary to the result of the previous report, no occurrence of the thrusting-power could be noted in either case