ADVANCED EXPERIMENTAL PHYSIOLOGY 171 



the end of a large thistle funnel, which is first covered with thin 

 rubber membrane, and then a large round hole is made in the 

 membrane by burning it with a soldering iron. The thorax is 

 opened in the pithed cat after establishing artificial respiration, 

 the pericardium is incised and the heart inserted through the hole 

 in the rubber membrane into the funnel and this connected with a 

 piston recorder. The rubber membrane fits snugly to the base of 

 the ventricles and renders the cardiometer air-tight. 



The carotid artery is connected as in the figure and the blood 

 returns to the jugular vein, the circulation being confined by ligatures 

 to the heart and lungs. The blood pressure is regulated by sinking 

 the tube more or less deeply in the mercury. 



CHAPTER XLII. (Advanced Demonstrations). 

 EFFECT OF HAEMORRHAGE AND SALINE TRANSFUSION. 



IN the anaesthetised and weighed animal a carotid cannula is 

 introduced and another in the jugular vein. A third cannula is 

 placed in the femoral artery. Observe the effect on the blood 

 pressure tracing (1) of bleeding from the femoral artery, (2) running 

 in physiological salt solution into the jugular vein. 



Note the volume of blood withdrawn and saline introduced. To 

 produce a fall of pressure 25 c.c. per kg. of body weight should 

 be removed. After running in the saline, bleed the animal to death, 



Fio. 173. Diagram of an oncometer and piston recorder. The rubber bands fasten the 

 glass lid in position. 



and note the effect on the blood pressure tracing and the quality 

 of the blood compared with that collected before transfusion. Look 

 for fluid in the abdomen and observe the organs after death. 



PLETHYSMOGRAPHS. 



Plethysmographs and Oncographs. In the pithed cat, trachea!, 

 jugular, and carotid cannulae are introduced. The abdominal cavity 



