IV] 



THE BLOOD AXD THE ORGANS OF CIRCULATION 



61 



111 the horse, and various other Ungulata in addition to the 

 chordae tendineae, there are other bands of tissue traversing the 

 ventricles. These are the moderator bands : they pass from wall 

 to wall, and tlieir function is to restrain the ventricles from 



Pulmonary 

 A rtery 



Pulmonary 

 Veins 



Musculus 

 pectinatus 



Rights 

 Auricle mt~ 



Right 

 Coronary . _ .9 

 A rtery 



Tricuspid , ' 

 \'alve 

 Chordae '" 

 tendineae 



Aortic valve 



\ Aeft 

 "^ A uricle 



J , Bicuspid 

 " valve 



_ _ Chordae 

 tendineae 



Ventricular 

 Septum 



. Musculus 

 papillaris 



Left 

 Ventricle 



Right ' 

 Ventricle 



Fig. 34. Section through heart of horse. 



undergoing undue distention. For this purpose they are 

 especialh' well developed in antelopes and other animals which 

 are fleet of foot, and in which cardiac strain might be supposed 

 to be exceptionally great. 



The complete course of the circulation in a mammal may now 

 be described. The venous blood coming from all parts of the 

 body enters the right auricle by the superior and inferior venae 

 cavae. It passes through the tricuspid valve to the right 

 ventricle ; thence it proceeds by the puhnonary arter3^ which 

 gives off a branch to each hmg : in so doing it is forced through 

 the semilunar valves. In the lungs the blood undergoes the 

 gaseous exchange which is an essential part of the respiratory 

 process, yielding up the waste carbonic acid gas, and absorbing 



