148 ELEMENTAKY PHYSIOLOGY. [XIV. 



3. Clamp the proximal end of the glass tube and 

 unclamp the elastic tube. Let the distal end of 

 the latter be quite open. Work the pump as 

 before. There being little resistance to the 

 outflow, the elasticity of the tube is not called 

 into play, and consequently the flow will be, as 

 in the case of the glass tube, intermittent. 



4. Working the pump as before, insert the fine 

 nozzle into the open mouth of the tube. Con- 

 siderable resistance will now be offered to the 

 outflow of fluid, the elasticity of the walls of the 

 tube will be called into play, and the water will 

 issue from the end of the tube in a continuous 

 instead of an intermittent stream. If the tube 

 be sufficiently long and sufficiently elastic in 

 proportion to the force and frequency of the 

 strokes, the flow will be absolutely continuous. 



B. MAJOR ARTERIAL SCHEME'. 



The pump represents the heart ; the small tubes 

 represent the resistance of the small arteries and 

 capillaries. The tubes on the proximal side of 

 this resistance represent the arteries, those on 

 the distal side the veins. 



1. The Mercurial Manometer. 



The manometer A is connected with the arterial, 

 V with the venous tubes. 



1 See Appendix. 



