150 



EXPERIMENTAL PHARMACOLOGY 



open, tie four strong ligatures into the margins of the sev- 

 ered walls as shown in Fig. 106, and with these ligatures tie 

 the chest firmly, leaving an opening about three or three 

 and one-half inches wide in a dog. This opening will be 

 smaller in a cat. Open the pericardium and stitch it to 

 the chest walls. 



X 7o recording 

 tambour 



Csrdi'ometer 



Pin hook to fasten into 

 ventricle 



Fig. 142. Cardiometer arranged for use as a myocardiograph. The pin is hooked 

 into the heart muscle and the cardiometer is held in a clamp. The beating of the heart 

 moves the membrane in and out. A tambour is used for recording. 



Various forms- of instruments are used to record heart 

 tracings directly from the heart. One is shown in Fig. 

 141. If you have such an instrument, suspend it in a clamp 

 from a stand over the heart. By two stitches made with a 

 needle in the upper and lower ends of the left ventricle 



