90 LABORATORY MANUAL OF GENERAL PHYSIOLOGY 



the beats are superimposed on oscillations in the base line. This is a 

 beautiful example of RHYTHMICITY (cf. Fig. 49 in Fulton's "Muscular 

 Contraction"). For a discussion of auricular tone see Bayliss, p. 540 or 

 Meek, Physiol. Rev., 7: 259, 1927; Fano, Beitr. z. Physiol., Ludwig's 

 Festschrift, p. 287, 1887. 



When the strip shows signs of exhaustion add to the solution 3 cc. 

 of 1% CaCU. Is there any change in the activity? If the activity is well 

 restored by the CaCU replace the contents of the beaker with 250 cc. of 

 0.7% NaCl containing 3 cc. of 0.9% KCl. What is the effect of K? 



Replace KCl with Ringer's solution. (This solution should maintain 

 prolonged contractions.) Text p. 436. 



16. Influence of Temperature on Turtle Auricles. — Make a preparation 

 of the auricles as in Ex, 15 (but do not slit auricles). Place the 250 cc. 

 beaker of Ringer containing the auricles and O2 tube in a wooden support 

 on a large jar (used as thermostat). Place a syphon in large jar to facili- 

 tate change of water for temperature change. A second jar (for replace- 

 ment) should be adjusted to next temperature desired. Register 

 contractions of the auricle on kymograph drum. Start at room tem- 

 perature. Go down to 9° or 8°C (if possible). Check at some intermedi- 

 ate temperatures. Then slowly go above room temperature and continue 

 to 25°. Take the time for ten beats. Choose temperatures distributed 

 about as follows: 25°, 24°, 22.5°, 21°, 19°, 17°, 16°, 14°, 12.5°, 11°, 9.5°. 

 Calculate the characteristic. Cf. Crozier, J. Gen. Physiol., 9: 543, 

 1925. The temperature graphs of hearts are remarkable for their absence 

 of "breaks" or critical temperatures. 



17. Effect of Adrenalin (Ex. 16 continued). — Apply adrenalin and 

 repeat temperature experiment. Place 1 cc. of adrenalin chloride solu- 

 tion in 100 cc. of Ringer. Take 1 cc. of this solution and add to the 250 cc. 

 of Ringer, in the beaker containing the heart. Do not prepare solution 

 until needed. The adrenalin shifts the axis of the graph without chang- 

 ing the slope showing that the master reaction is not changed. Three 

 well distributed temperatures will show the effect (cf. Crozier, J. Gen. 

 Physiol., 9: 541). 



18. Model of Mammalian Heart (Harvard Circulation Scheme). — 

 Pump = left ventricle. Valve in inlet tube to pump = mitral. Valve in 

 outlet tube = aortic. Bamboo cane (upper left) = resistance of small 

 arteries and capillaries. Tubes between pump and bambo = arteries; 

 those on distal side of this resistance = veins. Opening short circuit tube 

 (with clamp) at right of bambo tube = dilation of the vessels. Rim of 

 eccentric brass plate = intraventricular pressure curve of dog (periphery = 

 fractions of sec. radii = mm. Hg. pressure). 



Each revolution of the eccentric plate reproduces in the ventricular 

 tube both the time and pressure relations of the ventricular cycle in the 



