202 



THE CAT. 



[CHAP. vn. 



The whole inner wall of the heart is lined with a layer of 

 endothelium, which immediately invests a network of elastic fibres. 



Fig. 103. DIAGRAM OF THE COURSE OF THE CIRCULATION, SEEN DORSALLY. 



Aa. Arteries to alimentary tube. 



A 1 . Arteries to anterior parts of body and fore- 

 limbs. 



A*. Arteries to hinder parts of body and hind- 

 limbs. 



Al. Alimentary tube. 



Ao. Aorta. 



Ha. Hepatic artery. 



Hv. Hepatic vein. 



Let. Lacteals. 



Lg. Lungs. 



LA. Left auricle. 



Lr. Liver. 



LV. Left ventricle 



Ly. Lymphatics. 



PA. Pulmonary artery. 



P V. Pulmonary vein. 



HA. Right auricle. 



R.V. Right ventricle. 



T. Thoracic duct. 



V 1 . Veins from anterior parts of body and fore- 

 limbs. 



V s . Veins from posteiior part of body and hind- 

 limbs. 



VCI. Vena cava inferior. 



VCS. Vena cava superior. 



VP. Vena porta. 



The vessels which carry venous blood are dis- 

 tinguished by shading. Arrows indicate tliu 

 course of the blood-lymph and chyle. 



Thus the substance of the heart shows a similarity of structure to 

 that of the vessels which might be expected, since its walls are 



