330 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, 2, 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 thé venous system. In their 
