ELEMENTARY EXPERIMENTAL PHYSIOLOGY 



119 



diameter) into the left auricle, the other (5 cm.) into the aorta. The 

 brass tubes are connected by side tubes to the bottom and top respec- 

 tively of a reservoir containing water. A small hole is made in the 

 apex of the heart, and a glow 

 lamp is inserted into the left ven- 

 tricle. The wires of the lamp are 

 connected with two Grove cells. 

 A tube connected with a rubber 

 bag is tied into the apex. The 

 bag is full of water. On com- 

 pressing the bag the auriculo- 

 ventricular valves close, while the 

 aortic valves open. On relaxa- 

 tion the aortic valves close, while 

 the auriculo- ventricular valves open 

 (Fig. 116). 



The Cardiac Impulse. Observe 

 and feel the seat of the cardiac im- 

 pulse when the subject is (1) stand- 

 ing erect, (2) lying horizontal on 

 the left, and (3) on the right side. FIG ii6.-Gad's method of showing the 



' \ ' & action of cardiac valves. (Fredencq.) 



The impulse is felt in the fifth or 



fourth intercostal space about 1-|- inches below the nipple line, and 



3i inches from the mid-sternal line. It shifts under the sternum when 



Fir. 1 17. Marey's cardiograph. The tube is connected with a recording tambour. 

 Pressure is adjusted by the screw and spring. 



the subject lies on the right, and to the nipple line when he lies on the 

 left side. Owing to the influence of gravity, a different part of the 



