33 THE CIRCULATORY SYSTEM. 



On the plantar side of the foot small veins pass from the 

 digits to a superficial venous plantar arch, which lies just 

 proximad of the fibrous pad on the sole of the foot. At its 

 medial side this arch extends proximad and dorsad to join that 

 branch of the vena saphena magna which comes from the 

 dorsum of the second digit. On the lateral side it extends 

 proximad along the lateral margin of the foot, sends a com- 

 municating branch dorsad to the branches of the V. saphena 

 magna, and continues along the lateral border of the foot to 

 the ankle. It forms the beginning of the V. saphena parva 

 (Fig. 163, ^, page 401). This receives branches from the 

 lateral surface of the ankle, which anastomose with those of 

 the saphena magna. The saphena parva then passes proximad 

 along the lateral surface of the leg, close to its ventral border, 

 to the popliteal space. At the distal end of the popliteal 

 space it divides into two branches. One passes inward 

 through the fat of the popliteal space, receiving branches from 

 the lymphatic gland situated here, and joins the popliteal vein. 

 The other (') remains superficial and continues proximad over 

 the lateral surface of the biceps to the proximal end of that 

 muscle. Here it passes between the biceps and caudofemoralis 

 to join the inferior gluteal vein. 



IV. THE LYMPHATIC SYSTEM. SYSTEMA LYMPHATICUM. 



The lymphatic system of the cat has not been worked out 

 in detail, so that only the main features of the system are given 

 in the following account. 



The lymphatic system consists of a number of vessels, the 

 lymphatics, containing a colorless fluid called lymph, and of 

 lymphatic glands, connected with the lymphatic vessels. 

 The lymphatic vessels are found throughout the body as 

 slender tubes, frequently united into networks, and containing 

 many valves. They take origin from the spaces in the con- 

 nective tissue, so that they are at first without definite walls. 

 The fluid in the connective-tissue spaces gradually flows 

 together into 'tubes with definite walls, and these tubes, the 

 lymphatic vessels, finally join the venous system. In their 



