6/2 



PRINCIPLES OF GENERAL PHYSIOLOGY 



where they are called right and left auricles and ventricles, respectively. Fig. 

 225 is a schema of the circulation in birds and mammals. In the fish there 

 is only one circulation. The venous blood, arriving at the heart is sent first 

 through the aerating organs, the gills, from which it is distributed to the arteries 







Right heart 



Lungs 



Left heart 



FIG. 225. DIAGRAM OF THE MAMMALIAN CIRCULATION. 

 Venous'blood, black. Arterial blood, left white. 



of the body in general. In the amphibia and reptiles, part of the blood only 

 passes through the lungs, which may be considered to be one of the parallel 

 paths of the diagram. There are, however, arrangements by which a more or less 

 perfect separation of the aerated blood from the venous blood is effected, so that 

 the organs may have the benefit of that which contains most oxygen. Details of 



