Detailed observations on contraction of a single striated muscle fiber have been made under the interference microscope. Author directly observed contraction of such a fibre, which was produced dy applying rectangular pulse through a glass capillary electrode inserted into the fiber. Further, the contraction was photographed with a 8-millimeter cinecamera. The following results were obtained :
(1) Twitch : Contraction wave was propagated to the whole length of the fiber.
(2) Local continual contraction : It appeared only near the electrode, lasting during the passage of current.
(3) Decreasingly propagated contraction : The propagation was limited to a small distance from the electrode.
(4) Transition from local contraction to propagating contraction : This was cleary observed in the course of gradual increase of stimulating current.
(5) Minimum local contraction :
(6) Decreasingly propagated periodic contraction : A slow contraction wave of extremely short length started periodically at a certain point, during propagated for a limited length.
The above are gross classification of the way of contraction. Out of these, (1) and (2) are generally known, and also on (3) there are a few reports. However, (5) and (6) are scarcely known, and (4) has never been shown conspicuously, though its presence is generally assumed.
These types of contraction were presented with a 8-millimeter cinecamera for observation, and the results were reported.
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