LABORATORY MANUAL OF PHYSIOLOGY. 



a sidepiece to a pressure bottle, A . The open end of the tube is in- 

 serted into the aorta or pulmonary artery, above the semilunar 

 valves, and tied in. The ventricle behind the valves is cut away, 

 enough being left for the insertion and securing with a snugly tied 

 ligature of another glass tube which is connected through rubber 

 tubing with another pressure bottle, P, used for exerting pressure 

 on the ventricular side of the valves. Pressure bottle B is used 

 for the filling of P, and can be clamped off when this has been ac- 

 complished. 



Bottle P has had the bottom removed, and in place of it a heavy 

 rubber dam has been substituted. By raising or lowering bottle 

 A , the pressure on the arterial side of the valves may be increased 

 or decreased. The movement of the valves may be observed 

 through the glass plate of tube T. 



Make sudden pressure with the hand on the rubber membrane 

 of bottle P. Note the opening of the valve flaps. In which direc- 

 tion do they open ? Note their closure when the pressure on the 

 arterial side is greater than that on the ventricular side. Increase 

 the arterial pressure by elevating the bottle A . Note the increased 

 pressure needed at P to open the valves. What prevents the valves 

 from being forced back into the ventricle ? 



The same scheme may be utilized for showing the action of the 

 auriculo-ventricular valves by tying tube T into the auricle, and 

 the tube connected with bottle P into the ventricle, with the aorta 

 clamped off. 



XIX. MECHANICS OF THE CIRCULATION AS STUDIED WITH AN 

 ARTIFICIAL SCHEMA. 



Set up an artificial scheme of the circulation as shown in Fig. 

 33. H represents a Davidson's syringe having an inlet and an 

 outlet valve which correspond to the valves between the auricles 

 and ventricles and between the ventricles and arteries, respec- 

 tively. The fluid is, therefore, allowed to flow in one direction 

 only. A represents arteries, C capillaries, and V veins. Ma is a 

 manometer connected with an artery to show changes in arterial 



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