RECORDING HEART TRACINGS 



151 



fasten the lower ends of the two levers firmly to the heart. 

 As the ventricle beats air will be forced in and out of the 

 tambour on the apparatus. With rubber tubing connect 

 the apparatus to a medium sized tambour which records be- 

 low the blood-pressure on the drum. Cushny has devised 

 a myocardiograph which may be used to advantage. (Eber- 

 bach and Son Company, Ann Arbor, Mich.) With this in- 

 strument the drum must be brought to the side of the 

 animal. (See Fig. 317.) 



If no special apparatus is available, then a pin hook can 



To tambour 



-Thistle tube 



Ca rdiom eter 



Elastic rubber 

 dam 



Fig. 143. Cardiometer made from a large thistle tube. A hollow rubber ball with 

 an opening cut in one side and a tube in the other may be made into a cardiometer 

 by cementing a perforated rubber membrane over the opening in the side of the ball. 



be attached to the heart. A string is tied to the pin and 

 passed over pulleys to an ordinary (weighted) frog heart 

 lever which writes on the drum. Or a rubber membrane 

 (in the center of which a screw is attached, see Fig. 374) is 

 tied over a cardiometer (Fig. 142) and the string attached 

 to the heart by the pin hook is fastened to the screAv in the 

 membrane. The cardiometer is held in a clamp and con- 

 nected with a recording tambour. Another method of re- 

 cording heart tracings is shown in Fig. 144. 



When all adjustments are made place adrenaline solu- 



