128 



PEACTICAL PHYSIOLOGY 



arterial tube will oscillate at a height of about 4 to 5 feet. Notice in each 

 tube the cardiac pulsations and respiratory oscillations. The arterial 

 pressure rises in inspiration the venous in expiration. 



1. If the abdomen be compressed the pressures will rise in both the 

 artery and vena, but to a greater extent in the former. The heart is 

 better filled in diastole and the peripheral resistance is increased by the 

 compression of the splanchnic vessels. 



2. If the thorax be squeezed so as to compress the heart and prevent 

 its filling, the arterial pressure will fall very greatly, while the venous 

 pressure will rise slightly. The arterial manometer tube must be 

 again filled with sodium citrate solution before the arterial pressure is 

 again allowed to rise. 



3. If the administration of chloroform be pushed the arterial 

 pressure falls in a striking manner, while the venous pressure 

 rises slightly. In all these observations notice that the variations in 

 venous pressure are trifling compared with those of arterial pressure. 



CHAPTER XXXV. 

 BLOOD PRESSURE CONTINUED. 

 Demonstration. Record of Arterial Pressure, Effect of Excitation 





F 



Fro. 104. Arrangement of cannula, pressure bottle, and mercurial manometer for 



recording blood pressure. C, cannula ; p, p', clips ; F, float ; S, writing style. 



of the Vagus and Depressor Nerves. Effect of Gravity. Effect of 

 Asphyxia. A cat is anaesthetised with ether and chloroform, or 



