Chap. IV.] 



GENERAL PHYSIOLOGY. 



61 



We have seen that, in the pigeon or the rabbit, the heart is 

 like a double pump, or a pump with ,two completely separate 

 chambers placed side by side. One of these, the pulmonary 

 pump, forces blood into the lungs; the other, the systemic 



FIG. 23. PHYSIOLOGICAL DIAGKAM. 



1. Lung receiving blood from the right ventricle, 12. Here oxygen is 

 absorbed into the system, and carbonic acid gas and water are got rid 

 of by the system. 2. Left auricle receiving the arterialised blood from 

 the lungs. Thence it passes to 3, the left ventricle, to be distributed 

 by means of the arteries to the left of the figure. 4. Alimentary canal. 

 Here tissue nutriment is absorbed into the system, and is carried (1) 

 by the lacteal, 5, into the blood-stream returning to the heart ; and 

 (2) by the portal vein to the liver, 6, where bile is elaborated and 

 poured into the alimentary canal by the bile-duct, 7. The kidney, 8, 

 receives blood by a separate branch-artery. Here water and nitro- 

 genous waste are eliminated and pass out of the system by the ureter, 

 9.' Another branch artery carries blood to the senso-motor arc, 10. 

 The blood returns by veins (to the right of the figure) to the right 

 auricle, 11, whence it passes to the right ventricle, and so to the 

 ungs, 1. 



pump, forces to all parts of the body the blood delivered into its 

 receiver from the lungs. From all parts of the body the blood 

 collects in the receiver of the pulmonary pump. Thus all the 



