. A text-book of human physiology . 414 THE FUNCTIONS OF CROSS-STRIATED MUSCLES Muscles owe their color to a peculiar red pigment (myochrome) whichis closely related to haemoglobin but does not agree with it spectroscopically(K. A. H. Morner). § 3. STIMULATION OF MUSCLES AND OF NERVES A. THE MUSCLE CURVE 1. Method.—A muscular contraction can be recorded in several ways whichdiffer in principle but which finallj reduce to two groups, according as the short-ening induced bj- the stimulus is allowed to take place or not. In the latter case. Fig. 153.—Apparatus of Fick for recording variations in
. A text-book of human physiology . 414 THE FUNCTIONS OF CROSS-STRIATED MUSCLES Muscles owe their color to a peculiar red pigment (myochrome) whichis closely related to haemoglobin but does not agree with it spectroscopically(K. A. H. Morner). § 3. STIMULATION OF MUSCLES AND OF NERVES A. THE MUSCLE CURVE 1. Method.—A muscular contraction can be recorded in several ways whichdiffer in principle but which finallj reduce to two groups, according as the short-ening induced bj- the stimulus is allowed to take place or not. In the latter case. Fig. 153.—Apparatus of Fick for recording variations in the length and in the tension of a muscleartificially stimulated. By unhooking the tension recorder the lever, HH, is allowed to up and down like an ordinary muscle lever. For further , see text. the tension of the muscle increases as a result of the excitation, but its lengthremains constant. For this reason such contractions are called isometric con-tractions, and the variations of tension are recorded after Ficks method asfollows (Fig. 153). The muscle (M) is attached to a strong steel spring (f)which bears a long writing point (h) for magnifying and recording its move-ments. When the muscle is stimulated, it attempts to bend the spring, but sincethe latter yields but slightly, the muscle cannot shorten to any appreciableextent; consequently the whole effect of the muscular activity is to increase thetension. In the other method a lever loaded with a weight is commonly , andthe weight is so chose
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